How do you solve by substitution a = 3b - 4 and a + b =16?

2 Answers
Apr 2, 2018

b=5
a=11

Explanation:

a=3b-4 ----(1)
a+b=16----(2)

From (2),
a=16-b ----(3)

Sub (3) into (1)
16-b=3b-4
20 = 4b
b=5
a=11

Apr 2, 2018

a=11 and b=5

Explanation:

We know a in terms of b with the help of equation 1 a=3b-4

So put that that in equation 2,
3b-4+b=16
Add 4 on both sides
4b=20
Divide both sides by 4
b=5

Substitute that in one of the original equations

a+5=16
Subtract 5 from both sides
a=11

So a=11 and b=5