What is the answer to -3x-3y equals 3 and y equals 5x-17 using substitution?

It is set for substitution.

-3X - 3Y = 3

Y = 5X - 17 ( you have Y given to you, so substitute )

-3X -3(5X - 17) = 3

distribute

-3X - 15X + 51 = 3

-18X + 51 = 3

-18X = -48

X = -8/3

Now substitute back into first equation for Y

-3(-8/3) - 3Y = 3

8 - 3Y = 3

-3Y = -5

Y = 5/3

You preform the check ( it checks in first equation )