Answer:
See explanations below
Explanation:
Given the system of equation
2x - 10 y = -30 ... 1
x - 5y = 20 ... 2
Step: From 2;
x = 20 + 5y ...3
Step 2: Substitute equation 3 into 1
2x - 10y = -30
2(5y+20) - 10y = -30
Open the bracket
10y + 40 - 10y = -30
10y - 10y + 40 = -30
0+40 = -30
40 = -30
The steps taken by Teri are correct all through. He didn't make any error whatsoever