Question

The sum of two numbers is 400. If the first number is decreased by 20% and the second number is decreased by 15%, then the sum would be 68 less. Find the numbers after the decrease.

Answer 1

Let x = the first number
Let y = the second number

So we can set up two equations:
x+y = 400
.8x + .85y = 400-68

Use substitution:
y = 400 - x
.8x + (.85)*(400-x) = 332
.8x + 340 -.85x = 332
8 = .05x
x = 160

So that makes y = 240

We want the decreased values so:

160*.8 = 128
240*.85 = 204

So the answers are 128 and 204