Elimination was used to solve a system of equations.

One of the intermediate steps led to the equation 7x=21. Which of the following systems could have led to this equation?

a) 7x+2y=21, -7x-2y=21
b) 3x+2y=7, 2x-y=7
c) 4x+3y=24, -3x-3y=3
d) 8x-y=15, x+y=-6

1 answer

The correct system that could have led to the equation 7x=21 is:

a) 7x+2y=21, -7x-2y=21

In this system, when we add the two equations together to eliminate y variable, we are left with:

7x = 21

Therefore, the answer is option a).