You have 10th grade math?
0 balloons because if a set of balloons is 7 and Molly has a set less then it is 7-7=0

the L.C.M is 2
since it is the highest denominator.
so multiply through by the L.C.M


making x the subject.

dividing through by 3


0.
1/2 = 1/2
No need to add anything