Answer:
52 adults
Step-by-step explanation:
Let 'a' represent the number of adults at the movies. Then the number of children is (140-a) and the amount collected is ...
2.70(140-a) +5.25(a) = 510.60
2.55a +378 = 510.60 . . . . . . . . . simplify
2.55a = 132.60 . . . . . . . . . . . . subtract 378
a = 52 . . . . . . . . . . . . . . . . . . divide by 2.55
There were 52 adults at the movies.
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Additional comment
The number of children was 140 -52 = 88.
