The work is incorrect.
(-6) multiplies both terms inside parentheses. For some reason, the student changed the sign of that multiplier for the second term. The second term of the result should have a positive sign, the result of multiplying (-6)(-2/13) = +12/13.
3 to the power of 3 is 9 or 3x3=9
9/3=3
A = L x W = 8 x 17 = 136
answer
C. 136 sq. units