To find y: a straight line equals 180° so the equation to solve is 5y+155=180 (5y and 155 make a straight line) when you solve you get y=5. For X: we now know that 5y is 25° (if y=5 then plug 5 into 5y to get 25) and because the other angle is a right angle that measures 90° then the other angle must also measure 90. Set up the equation 25+13x=90. You should get X=5. Hope this helps explain!