Solve using substitution

Question

4x + 6y = -18

3x + 4y = -11

Show steps to solve using substitution.

Answer 1

The system of equations are

4x + 6y  =  - 18 ------------------>  (1)

3x + 4y  =  - 11 ------------------>  (2)

From the equation (1)

4x  =  - 18 - 6y

x  =  (- 18 - 6y) / 4

x  =  - 18/4 - 6y/4

x  =  -9/2 - 3y/2

Substitute x  =  -9/2 - 3y/2 in Eq (2)

3(-9/2 - 3y/2) + 4y  =  - 11

- 27/2 - 9y/2 + 4y  =  - 11

(- 9y + 8y)/2  =  - 11 + 27/2

(- 9y + 8y) / 2  =  (- 22 + 27) / 2

(- y )  =  5

y  =  -5.

Substitute y = -5 in  x  =  -9/2 - 3y/2

 x  =  -9/2 - 3(-5)/2

     =  -9/2 + 15/2

     =  (-9 + 15) / 2

     =  6 / 2

x  =  3

The Solutions are x = 3 and y = - 5.

Answer :

The Solutions are x = 3 and y = - 5.