3x+4y=15 and 2x-4y=30 Solving systems of Equations using Substitution and elimination

Question

Some Algebra 1 ive need some help on.

Answer 1

Elimination method

3x+4y = 15 -----> (1)

2x-4y = 30 --------> (2)

To eliminate the y value add the equations (1) and(2).

3x+4y = 15

2x-4y = 30

_________

5x = 45

Divide to each side by 5.

5x/5 = 45/5

x = 9

Substitute the x value in (1).

3*9+4y = 15

27+4y = 15

Subtract 27 from each side.

27-27+4y = 15-27

4y = -12

Divide to each side by 4.

4y/4 = -12/4

y = - 3

Solution is x =9, y = -3.