Question

-3x-4y =20
x-10y= 16

If x,y is the solution to the system of equations above what is the value of x?

A. -14
B. -12
C. -4
D. 16

Answer 1

-3x-4y =20
x-10y= 16

-3x -4y = 20
3x -30y = 48
-34y = 68
y = -2

x - 10(-2) = 16
x + 20 = 16
x = -4

Answer 2

- 3 x - 4 y = 20

Multiply both sides by - 2.5


- 2. 5 ∙ ( - 3 x ) - ( - 2.5 ) ∙ 4 y = - 2.5 ∙ 20

2. 5 ∙ 3 x + 2.5 ∙ 4 y = - 2.5 ∙ 20

7.5 x + 10 y = - 50


x - 10 y = 16
+
7.5 x + 10 y = - 50
______________

x + 7.5 x - 10 + 10 = 16 - 50

8.5 x = - 34

x = - 34 / 8.5 = - 4