Solve this equation using substitution method a-2b=9 2a+3b=4

Answer 1

Isolate a for :

a - 2 b = 9

Add 2 b to both sides

a = 9 + 2 b

a = 2 b + 9

Put this value in equation:

2 a + 3 b = 4

2 ( 2 b + 9 ) + 3 b = 4

4 b + 18 + 3 b = 4

7 b + 18 = 4

Subtract 18 to both sides

7 b = - 14

b = - 14 / 7

b = - 2

Put this value in equation:

a - 2 b = 9

a - 2 ( - 2 ) = 9

a + 4 = 9

Subtract 4 to both sides

a = 5

The solutions to the system of equations are:

a = 5 , b = - 2