Question

Which expression is a factor of 4xy – 4x + 3y – 3?

Answer 1

Well y = 1 and x = -3/4

Answer 2

Since it is just an expression (there is no equal sign) You need to just factor it.

For the first two terms factor out the common 4x giving you 4x(y-1)
For the last two terms factor out the 3 giving you 3(y-1)
Now put it together giving you (4x+3)(y-1)
If it had been an equation equal to zero, then @emilyowl answer would be meaningful.