Hmm i counted like this

1 star is 7 so 3 x 7 =21

1 broom is 3 so 3 + (3+3) +3 = 12

Now the witch, each of them holds 1 star and 1 broom so I think 1 star + 1 broom = 7+3=10

So in the equation of the witch

30 + 15 (each witch is 5) = 45

In the end, broom + (only witch x 2 stars)

=> 3 + (5 x 14) = 73