Question

A mixture contains 40oz of glycol and water, and it is 10% glycol. The mixture is to be strengthened to 25% by adding glycol. How much glycol is in the original mixture?

Answer 1

I found 50, making a rule of three where
 40__10
  x___25

x=10
 40+10= 50
( I hope I'm right, but from what I understand this would be the resolution)