Question

If 3x - y = 3 and -x + y = 3 then xy=___?

Answer 1

First find x and y.

Solve system of equations by elimination.

  3x-y=3

+(-x+y=3)

---------------

2x=6

x=3

Now plug in x into one of the equations to find y.

-3+y=3

y=6

xy=3x6=18