system of equations substitution (2a=3b-13 and -b=-2a-7)

Question

This is my problem  2a=3b-13

                              -b=-2a-7

Answer 1

2a = 3b - 13              eq1

 

-b = -2a - 7    ------->   b = 2a + 7           eq2

 

 

Since b is defined from eq2, we can substitute eq2 into eq1 and solve for a.

 

2a = 3(2a + 7) - 13

2a = 6a + 21 - 13

-4a = 8

   a = -2

 

Next, substitute this value of a into eq2 to solve for b.

 

b = 2a + 7

b = 2(-2) + 7

b = -4 + 7

b = 3

 

Your solutions are

 

a = -2

b = 3