Ok, for this one... see the picture
Step 1: Find angle R by adding angle Q and P then subtract from 180 (all angles add to 180). That gives us R angle of 70 degrees.
Step 2: Find angle QRX by subtracting angle R from 180 (the 2 angles that make up the straight line will add to 180). 180 - 70 = 110 degrees.
Step 3: Find y by setting the equation to the answer we found in step 2.
y + 25 = 110
y = 85 degrees
Check out the picture. It should help.