X = - 2y + 300

3y = 800 - 4x

y=80, x=140

Step-by-step explanation:

When you solve with subsitution, you first need to subsititute x=-2y+300

This then becomes: 3y=800-4t (-2y+300)

For x=-2y+300

Isolate y for 3y=800-4 (-2y+300):

y=80

For x=-2y+300, subsitute y=80

x=-2*80+300 = 140

So x=140