Question

Solve the system using substitution.
3x+5y=15 2x+4y=8

Answer 1

x=10

y=-3

Explanation:

3x + 5y= 15...eqn. 1

2x + 4y= 8...eqn. 2

multiply eqn. 1 by 2 and eqn. 2 by 3

6x + 10y = 30...eqn. 3

6x + 12y = 24...eqn. 4

0 - 2y = 6

divide both sides by the coefficient of y which is -2

- 2y = 6

- 2 -2

y= -3

Put y= -3 into eqn. 1

3x + 5(-3) = 15

3x - 15 = 15

3x =15 + 15

3x = 30

3 3

x = 10

Therefore X= 10 and Y= -3