Question 115827
x+y=80 or x=80-y
x=2y-70 now replace x with(80-y) in the second equation:
80-y=2y-70
-3y=-150
y=-150/-3
y=50 answer.
x+50=80
x=80-50
x=30 answer.
proof
30=2*50-70
30+100-70
30=30