Question

Which value of x satisfies both -9x + 4y = 8 and -3x − y = 4?

a.-1/7
b.-7/9
c.-8/7
d.-9
e.-4/3

Answer 1

cancel y values
multiply 2nd equation by 4 and add to first

-9x+4y=8
-12x-4y=16 +
-21x+0y=24

-21x=24
divide both sides by -21
x=24/-21
x=-8/7

C is answer