I have the following:

A minimum charge of $70
I have to average $110 per order.
I have 4 breakdowns that have the following percentages of charges.

1-25 = 20%
26 - 50 = 35%
51-75 = 30%
76 + = 15%

Is there a way to calculate, via a formula, what the increase of charges should be for each breakdown in order to come up with an average of $110 all the time?

Isn't there a relationship between the percentages, that when applied to $110 will always reflect a weighted average of $110?

Chris