Question

Solve this system using the substitution method.
a – 4b = 2
5a = 3b – 7
Solve using the substitution method and be sure to show all of your work.

Answer 1

since a = 4b+2, use that to get
5(4b+2) = 3b-7
solve for b, and then you can get a

Answer 2

Write a - 4b = 2 as a = 4b+2, thus:

5a = 3b - 7
5(4b + 2) = 3b - 7
20b + 10 = 3b - 7
17b + 10 = -7
17b = -17
b = -1

Therefore, a - 4b = 2 --> a - 4(-1) = 2 --> a + 4 = 2 --> a = -2

This means that a = -2 and b = -1