All angles in a triangle add up to 180 so 180 - 60 = 120 then 180 - 155 = 25 then 25+65 = 90 that is the remaining angle but finally 180 - 90 = 90 is the missing angle
if its wrong that means you didn't explain it correct tell me if its wrong and ill solve it correctly if you say what's the width, length and height the answer is down below.