Answer:
part 7 = 15cm
Step-by-step explanation:

It will be 55 because I use this for my class
2 x
----- = ------
3 15
cross multiply
(3)(x) = (15)(2)
3x = 30
x = 30/3
x = 10
so 2/3 = 10/15.......notice how these are equivalent fractions....that is because proportions are nothing but equivalent fractions