xy is equal to x times y.
Steps?
xy+x+y=z
--combine x's and y's
2x+2y=z
--solve by moving over equals
2x=z-2y
or
2y=z-2x
Can't add xy to x+y, doesn't work like that.
eg (just making up numbers here)
let's say x = 2 and y = 3
(2x3)+(2)+(3)=11
if we sub x = 2 and y = 3 into your equation,
2(2)+2(3)=10
edit
is this a problem you were given or is it made up?