Question

Solve 20x+ 5y = 15 for y.

Answer 1

20x+ 5y = 15

Move 20x to the other side. Sign changes from +20x to -20x

20x-20x+5y=-20x+15

5y=-20x+15

Divide both sides by 5

5y/5=y ( Cross out 5 and 5, divide by 5, 1*1*y=y)

-20/5=-4x

15/5=3

y=-4x+3 or y=3-4x

Answer: y=-4x+3 or y=3-4x