I need to solve these two equations using either substitution or elimination
1/4x – 1/2 = 5
3x + 2/3y = -40

Question

I need to solve these two equations using either substitution or elimination  1/4x - 1/2 = 5  3x + 2/3y = -40

Philomena · Answer

Answer:

y = -15

x = -10

Step-by-step explanation:

1/4x – 1/2 = 5 (1)

3x + 2/3y = -40 (2)

Multiply (1) by 4

1/4x – 1/2 = 5

1/4x * 4 – 1/2y * 4 = 5 * 4

4/4x – 4/2y = 20

x – 2y = 20 (3)

Multiply (2) by 3

3x + 2/3y = -40 (2)

3x * 3 + 2/3y * 3 = -40 * 3

9x + 6/3y = -120

9x + 2y = -120 (4)

x – 2y = 20 (3)

9x + 2y = -120 (4)

Using elimination method, Add (3) and (4)

9x + x = -120 + 20

10x = -100

x = -100/10

x = -10

Substitute x = -10 into (3)

x – 2y = 20 (3)

-10 – 2y = 20

-2y = 20 + 10

-2y = 30

y = 30/-2

y = -15

x = -10