Question

If the first equation is multiplied by 3 and then the equations are added, the result is _____.

Answer 1

When you multiply the first equation by 3, you get:
3 × 3x = 9x
3 × y = 3y (but when added, that part gets eliminated)
3 × 3 = 9
So you end up with
9x + 3y = 9
x - 3y = -2
(add)
10x = 7

So your answer is B. 10x = 7. I hope this helps!