Question

Two equations are given below:

Answer 1

a is given to us so just plug a into the first equation:

b-3 - 3b =9

Add 3 to both sides:

b-3b=12

Combine like terms:

-2b=12

Divide by -2 to get b by itself:

b=-6

The only answer with b as -6 is the first one, (-9,-6)

Answer 2

The first one, (-9,-6) because if you were to plug it in the answers would equal therefore, the equation is true.