 Under the chapter of consumer behavior, we are having the sign of the substitution. Mean the substitution effect, what sign it will carry due to the change in the commodities price. As we know that the consumer demand, it will change with respect to the change in the price. If price of the commodity will decrease, consumer will enhance its demand. If price of the commodity will increase, consumer will decrease its commodity quantity demanded. So it means there will be the inverse relationship between the price and the quantity demanded. It means they both go into the opposite direction and we can say that if there will be any change in the price due to the substitution, it should be the positive effect or it should be the non-active effect. So the substitution effect, it will be called the positive effect. If the consumer is always selecting the best bundle because if he is having 1, 2, 3 or any type of the bundle, he is having the tendency to have his optimal choice that is provided to him with the available resources that the consumer will select, always the best available choice. So if the consumer is now shifting his optimal choice bundle as compared to the previous, at least we should consider that even this bundle, it should be as much as best or as much maximizing of utility as the previous. If there is decrease in the price, we see that the consumer has reduced and the consumer's budget line where the amount of commodity consume is less than at the bundle at. So here the consumer was consuming his original budget line and now the consumer is having this. This was his original budget line and with the decrease in the price, now consumer has shifted towards this budget line and this movement of the pivot, it shows that this part of the original budget line was already available to the consumer and now if the consumer has to select any bundle, it is not possible that consumer will select any bundle less than that optimal bundle means whatever now the consumer will select, it must have at least this much amount of the X1 that he is having and he must have some additional to this added to this because this he was having on his original budget line. Now with the added budget line, there must be some more of that commodity whose price has decreased and this curve also shows us at this graph that now with the change in the slope of the budget line and this pivoted line that we have showed in the form of this green that the consumer has shifted from X to point Y and in selecting this bundle of Y, now consumer has commodity of X this much and up this added amount from this point to this is again consumer is having and this added amount is due to the substitution effect and these bundles were already affordable X to him and the Y but now the consumer that have were not able to purchase but now the consumer has purchased more. So keeping in view this as we examine this situation that the substitution effect it will always be positive in the form that if the consumer will affect the best optimal choice bundle. So keeping in view this if price will decrease consumer will increase the commodity demanded and if consumers having a option when the price decreases consumer will increase but if price will increase consumer will decrease but in the form that the substitution effect it will be the positive sign for the consumer and the optimal choice on the pivoted budget line must be the bundle at least that it should not be less than that the previous bundle. So the substitution effects positive sign will be utilized in the calculation of our total effect when we calculate the change in the commodity quantity demanded due to the change in the price. So this diagram shows that with the change in the price and here we have seen the change in the form of the decrease in the price of X1 that now the new optimal choice bundle that the consumer will select it must involve the previous amount of X1 and some other amount of the X1 so bundle Y will have at least the previous amount of X1 and some added. So substitution effect moves opposite to the price movement in the form and it will give the negative effect. So the substitution effect it shows that if price increases demand will decrease and if price decreases demand will increase due to the substitution effect. Thank you.