-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
-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
2 answers
- 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
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
2 answers