 Hello and welcome to the session. In this session we discussed the following question which says simplify 15x plus 9x within parenthesis divided by 6 minus 1 upon 2 of 18x. Before we move on to the solution, let's discuss the board mass rule for the simplification of the algebraic expressions. Here B stands for the brackets that is first we remove the brackets O is for of then we simplify of D is for division that is next we would do division M is for multiplication that is after division we do the multiplication then after this we do addition then we do the subtraction. This is the key idea that we use for this question. Now we move on to the solution. We need to simplify the algebraic expression 15x plus 9x within parenthesis divided by 6 minus 1 upon 2 of 18x. So according to the board mass rule first of all we need to solve the brackets. So here we have the brackets here. So first we will solve the expression within these brackets. So this would be equal to 15x plus 9x which is 24x divided by 6 minus 1 upon 2 of 18x. According to the board mass rule next we have O that is of so next we will simplify of which is this. So further we get this is equal to 24x divided by 6 minus now 1 upon 2 of 18x means 1 upon 2 multiplied by 18x now 2 9 times is 18 so this is equal to 9x. So here we have 9x in the next step we do the division. So we have 24x divided by 6 now 6 4 times is 24 so this is equal to 4x so this is equal to 4x minus 9x. In the next step we would do the multiplication according to the board mass rule but we don't have any multiplication to be done here. Neither we have to do the addition now we have to just do the subtraction. So now 4x minus 9x gives us minus 5x. So on simplifying this expression we get minus 5x so minus 5x is our final answer. This completes the session hope you have understood the solution of this question.