 Hello and welcome to the session. In this session we discussed the following question which says find a-b and b-a in the following. First, we have set a is equal to the set containing the elements 2, 3 and 6 and a set b is the set containing the elements 1, 3, 7, 10. In the second part we have a is the set of letters of the word crowd and b is the set of letters of the word crowd. Before we move on to the solution, let's see what is the difference of the two sets a and b. First we have a-b. It is the set containing the element x such that x belongs to set a and x does not belong to the set b. Then next we have b-a which is the set containing the element x such that x belongs to set b and x does not belong to the set a. This is the key idea that we would use for this question. Now we move on to the solution. In the first part, we have set a is the set containing the elements 2, 3, 6 and b is the set containing the elements 1, 3, 7, 10. We have to find a-b and b-a. Now a-b would be the set containing the elements that belong to the set a but do not belong to the set b. Consider element 2 of set a. This belongs to set a but does not belong to set b so this would be included in the set a-b. Next element of set a is element 3. This is included in set b also so this would not be included in the set a-b. Then we have the element 6 which is not included in set b so this would be included in a-b. So a-b is the set containing the elements 2 and 6. Next we are supposed to find out b-a. This would be the set containing the elements that belong to the set b but that do not belong to the set a. Now we consider each element of the set b one by one. First we have element 1. It belongs to the set b but it does not belong to set a so it would be included in the set b-a. Then we have the element 3 which is included in set a also so it won't be included in set b-a. Then we have 7 which is in set b but not in set a so we can write this in the set b-a. Then we have the element 10 which belongs to the set p but does not belong to the set a. So set b-a contains the elements 1, 7 and 10. So this is the answer for the first part of the question. Now next we have set a which is the set of the letters of the word crowd and set b is the set of the letters of the word crown. This means a is the set containing the elements c, r, o, w and d. b is the set containing the elements c, r, o, w and n. Now we need to find out a-b and b-a. First let's consider a-b. This would be the set containing the elements that belong to the set a but that do not belong to set b. Now consider the element c of set a. It belongs to set b also so this means it won't be included in a-b. In the same way elements r, o and w they belong to set a and b both so they won't be included in the set a-b. Then we have the element d or set a which is present in set a but not in set b so we would include this element in the set a-b. Thus we get a-b is the singleton set containing the element d. Now consider b-a. This would contain the elements that belong to the set b but does not belong to the set a. As you have observed that the elements c, r, o, w are common to both the sets a and b. Now consider the element n of the set b. This belongs to set b but does not belong to set a so it would be included in the set b-a. And rest of the elements of the set b won't be included in the set b-a since they are also present in the set a. So we have b-a is the singleton set containing the element n. So this is the final answer for the second part of the question. This completes the session. Hope you have understood the solution of this question.