2014 · Q24
The sum of two positive numbers x and y is 2.5 times their difference. If the product of the numbers is 84, then what is the sum of the two numbers?
Elementary MathematicsAlgebra
- A26
- B24
- C22
- D20
Explanation
x + y = 2.5(x - y) and xy = 84 give (x+y)^2 = (2.5d)^2 with (x-y)^2 = (x+y)^2 - 336; solving yields x + y = 20.