Some Gmat Prep

Hi , i would appreciate if someone could wrote his way of solving the following: 1. If x*y+z = x(y+z), which must be true? a. x=0 z=0 b. X=1 y=1 c. x=1 z=0 i could find out that x=1 but i cant really get to z=0( the answer is c.). I mean if you solve the equation one gets...z=x*z -->this leads to x ...