Suni needs to solve the system of equations using addition. What variable should she solve for first? Find the solution.
- 5x + 3y = 15
2x – 3y = - 15
What variable should Suni solve for first?

solve for x first

Step-by-step explanation:

Given the 2 equations

- 5x + 3y = 15 → (1)

2x - 3y = - 15 → (2)

Add the 2 equations term by term to eliminate y

- 3x + 0 = 0

- 3x = 0

x = 0

Substitute x = 0 into either of the 2 equations and solve for y

Substituting into (2)

2(0) - 3y = - 15

- 3y = - 15 ( divide both sides by - 3 )

y = 5

solution is (0, 5 )

option 3 . (5x + 1) - (-10x + 6)

step-by-step explanation:

option 1 :

(4x + 3) + (-9x + 4)

or 4x+3 -9x + 4

or -5x + 7

option 2

(x - 2) - (6x - 9)

or x-2-6x + 9

or -5x + 7

option 3

(5x+ + 6)

or 5x + 1 + 10x -6

or 15x -5

option 4

-4x+2x+7-3x

-7x + 2x + 7

-5x + 7

hence only option 3 did   not satisfy the given simplify expression.