Which equation models this problem?
chelsea paid $54.90 for nine bath towels. what is the unit price, p, per towel?
a. 54.90p = 9
b. 9p= 54.90
c. p/9 = 54.90
d. p/54.90 = 9

What we need to do  is divide the total prize by the number of units, that is by 9:

we know this because 9 of those pieces, or 9p is equal to  54.90

so the right equation is B. 9p= 54.90

(another possibility would be p=54.90/9)