Five friends P, Q, X, Y and Z purchased some notebooks.

Five friends P, Q, X, Y and Z purchased some notebooks.

The relevant information is given below: 1. Z purchased 8 notebooks more than X did. 2. P and Q together purchased 21 notebooks. 3. Q purchased 5 notebooks less than P did. 4. X and Y together purchased 28 notebooks. 5. P purchased 5 notebooks more than X did. If each notebook is priced ₹40, then what is the total cost of all the notebooks?  (UPSC CSE Prelims CSAT 2022) (a). ₹2,600 (b). ₹2,400 (c). ₹2,360 (d). ₹2,320 Solution :  Let's represent the number of notebooks purchased by each friend with the respective letter (P, Q, X, Y, Z) and use algebra to solve for their values. From statement 1, we know that: Z = X + 8 From statement 2, we know that: P + Q = 21 From statement 3, we know that: Q = P - 5 From statement 4, we know that: X + Y = 28 From statement 5, we know that: P = X + 5 We can use these equations to solve for each variable. Starting with P and Q, we can substitute equation 3 into equation 2 to get: P + (P - 5) = 21 2P - 5 = 21 2P = 26 P = 13 And since Q = P - 5, we have: Q = 8 Next, we can substit…