Don't mind my work but can someone give the answer for 50

The answer to question 50 is A. 240 square feet

The surface area of Micah's ramp is 
          (12 + 13 + 5 ) * 6 + 2 ( 1/2 * 12 * 5 )
                    30         *  6 +           60
                              180     +          60
                                           240 ft

(-0, -7) is your answer