American airlines made a total money of $ 4263
Solution:
Given that,
Cost of 1 first class ticket = $ 53
Cost of 1 coach ticket = $ 21
There were 139 passengers total
30% of the passengers composed of the first class, Which means 30 % of 139 are first class
Number of first class passengers = 30 % of 139

Thus approximately 42 passengers are from first class
Number of coach class passengers = 139 - 42 = 97
So we have,
Number of first class passengers = 42
Number of coach class passengers = 97
To find: Total money made by American airlines
We can frame a equation as:
total money = (Number of first class passengers x Cost of 1 first class ticket) + (Number of coach class passengers x Cost of 1 coach ticket)

Thus american airlines made a total money of $ 4263