Answer:
9 (5e - 3f)
Step-by-step explanation:
45e -27f
45e = 9*5*e
27f = 9*3*f
The common factor is 9
9*5*e - 9*3*f
Nia did the chores the more
100 is more than 20
31 pieces
6 + 5 x 5 = 31