Solve this system of equations using substitution.

Question

(a = 3b - 4)

(a + b =16)

Answer 1

Substitution method :

The equations are

a = 3b - 4    ---------> (1)

a + b = 16   ---------> (2)

Substitute a = 3b - 4 in (2).

a + b = 16

(3b - 4) + b = 16

3b - 4 + b = 16

4b - 4 = 16

4b = 16 + 4 = 20

⇒ b = 5.

Substitute b = 5 in (1).

a = 3(5) - 4

a = 15 - 4

a = 11.

Solution of given system is a = 11 and b = 5.