Solve this system of equations using substitution Please! (b + 5a = 150) and (b + 7a = 216)

Question

b + 5a =150,

b + 7a =216

Answer 1

line 1: b+5a=150

line 2: b+7a=216

subtrakt line 1 from line 2

2a=216-150=66

a=33

from line 1: b+165=150

b=150-165=-15

Answer 2

b+5a =150.......A

b+7a =216.......B

Solution

b = 150-5a

150-5a+7a=216

-5a+7a=216-150

2a/2=66/2

a=33

Substitude the value of a in eguition A

b+5(33)=150

b-165=150

b=150-165

b=-15

Check

-15+5(33)=150

-15+7(33)=216