Question

which ordered pair is a solution of the system of equations

y=-3/5x

x-3y=-42

A.(70,-42)

B.(-21,63/50)

C.(5,3)

D.(-15,9)

Answer 1

y=-3/5x
x-3y=-42

Plug the first one into the second one, for 'y' :

x - 3(-0.6x) = -42
x + 1.8x = -42
2.8x = -42

x = -42/2.8 = -15

Plug this back into the first equation above:

y = -0.6(15) = 9

The 'ordered pair' is (-15, 9). That's choice (D.).