Question

If you were to use the substitution method to solve the following system, choose the new equation after the expression equivalent to x from the second equation is substituted into the first equation.
2x – 3y = –29
x + 4y = 13

2(4y + 13) – 3y = –29

2(–4y + 13) – 3y = –29

2x – 3(4y + 13) = –29

2x – 3(–4y + 13) = –29 ...?

Answer 1

The answer is 2(–4y + 13) – 3y = –29

Step 1: Express x from the second equation
Step 2: Substitute x into the first equation:

The system of equations is:
2x – 3y = –29 
x + 4y = 13

Step 1: 
The second equation is:    x + 4y = 13
Rearrange it to get x:         x = - 4y + 13

Step 2:
The first equation is:          2x – 3y = –29 
The second equation is:    x = - 4y + 13
Substitute x from the second equation into the first one:
2(-4y + 13) - 3y = -29

Therefore, the second choice is correct.