Hannah wanted to check her solution of b=-3 for the equation 9/7 (1+b)-6/7b 1=1 . Substituting b for -3, she writes the following:
A. 9/7(1+(-3))-6/7b+1=1
B. 9(1+(-3))-6(-3)-7=7
C. 9(1+(-3))+18+7=7
D. 6-18+7=7
E. -12+7=7 -5=7
F. -5=7
In which line did Hannah make a mistake? Choose one.