What is a and the answer?

5(2a-2)=7(a+8)-27   Use distributive property

10a-10 = 7a+56 - 27       Add 10 to both sides

10a  =  7a + 56- 27 + 10    Subtract 7a from both sides

10-7a = 56-27+10              simplify

3a = 39                          divide both sides by 3

a = 13

Its actually

10a-7a=56-27+10

3a=39

a=13