Question

Solve for x and y by deriving an expression for y from the second equation, and substituting it back into the first equation.

−x−3y=1
5x+3y=−8

Answer 1

5x+3y=−8 ----> 3y = -5x -8
y = (-5/3)x -8/3
replace in equation 1 -->
-x -(-5x -8) = 1
4x+8 =1
x = -7/4
y = (-5/3)x -8/3 = 35/12 - 8/3 = 3/12 = 1/4