0.2x + 0.5y = 4

-0.1x + 0.3y = - 2

Your solving for variable x

do move all the terms containing x to the left and all other terms to the right

so we going to add - 0.5y to each side of the equation

0.2x + 0.5y + - 0.5y = 4 + - 0.5y

them combine like terms 0.5y + - 0.5y = 0.0

0.2x + 0.0 = 4 + - 0.5y

0.2x = 4 + - 0.5y

Divide each side by 0.2

x = 20 + - 2.5y

x=20 + - 2.5y