Solve the literal equation for y.

2x-4y=20

2 (13) 13 = x

2 • 13 = 26

26-20 = 6

4 (2) = 6

y = 2

I first multiplied 4 times a number bigger than 20. It must equal an even number. I then multiplied 4 times a number that would equal six when doing 4•y. I subtracted the equation to check my answer.

Y = 1/2x - 5

Take the original equation:

2x - 4y = 20 - - - > subtract 2x

-4y = - 2x + 20 - - - > divide by - 4

y = 1/2x - 5