|4^(x+y)=16 => |4^(x+y)=4^2 => |x+y=2 => |x=2-y => |x=2-y => |x=4
|4^(x+2y)=1 |4^(x+2y)=4^0 |x+2y=0 |2-y+2y=0 |2+y=0 |y=-2
|4^(x+y)=16 => |4^(x+y)=4^2 => |x+y=2 => |x=2-y => |x=2-y => |x=4
|4^(x+2y)=1 |4^(x+2y)=4^0 |x+2y=0 |2-y+2y=0 |2+y=0 |y=-2