For what values of y does the following equation have no solutions for x?

xy + 5y - 4x + 20=1

We can use simons favorite factoring trick,

The "xy+5y part can be factored into y(x+5)

We can add 8x so that it is 4x+20 which is 4(x+5), then we can comping and it is (y+4)(x+5)-8x=0

can you take it on?