Question

1.

Answer 1

1. Choose C. When you want to eliminate a, the equation has to have opposite values that cancel out. If you already have 4a, you want to get -4a, which is -4*a shown in the third option.

2. -3. Since we already have 3 y, we want -3 y so it can cancel out since 3-3=0.

3. -6. We have 6x already so we want -6x to cancel out since 6-6=0.

4.
-5x+20y=-35
5x+9y=6
29y=-29
y=-1

5x+9(-1)=6
5x-9=6
5x=15
x=3

Final answer: (3,-1)

5. The error is in step 2 since they forgot to multiply -2(10)