Question

The price of a book A is 3 times more than that of book B.if the price of B is increased by 20% and that of A is reduced to 60%, then the percentage decrease in the sum of the prices of the book A and B is

Answer 1

Let price of book A be a
Price of book B be b
a = 3b
Therefore total cost of Book A and Book B = a + b = 4b
When, price of book B is increased by 20% then new price = 1.2b
When price of book A is reduced to 60% = 0.6a
new total cost of both books = 1.2b + 0.6a = 0.6(a+2b) = 0.6(3b + 2b) = 3b
Decrease in sum of price of book = $\frac{(3b-4b)}{4b}$ = 25%