Answer:
The answer would have to be shown in your working out, so look down below for an explanation.
Step-by-step explanation:
You would make each equation with the same letter equal to each other
5x- 10= 7x-20
3y= 5y-16
Then you would solve the equations
5x-10 = 7x-20
+20 +20
5x +10= 7x
-5x -5x
10= 2x
x= 5
-
3y = 5y-16
+16 +16
3y+16=5y
-3y -3y
16 = 2y
y = 8
And there's how you would prove that x=5 and y=8