angles

Right, so this is a pentagon. The sum of the internal angles in a pentagon is 540°. 

135+112+y+88+90=540

Solve for y.

I think you can do the rest yourself.

the sum of the angles in a pentagon is 540, so 540-90-112-88-135=115

Because it is a hexagon, we know there are 540 degrees total. so 540-135-112-88-90=y, simplifying to $y=\boxed{115}$