Question

Solve for x,y, and 15

Answer 1

27

Explanation:

x + y = 15 (gallons) (1)

0.25*x + 0.10 * y = 0.15 * 15 (2)

Multiply 100 on (2):

25x + 10y = 15

Divede by 5

5x + 2y = 3 (3)

From (1) y = 15 - x

so 5x + 10*(15 - x) = 15

5x + 150 - 10x = 15

-5x = 15 - 150 = -135

x = 135/5 = 27 (gallons)