Answer:
He makes a card= +10
He goes to the Movie Theater 11 times= +77
10+77= 87
-10 -10
?(7) = 77
7 7
? = 11
Free movie, F = 87pts
Initial reward, I = 10pts
Additional reward, A = 7pts
Movie visit, X
F = I + XA
87 = 10 + 7X
X = (87-10)/7
X = 11
After 11 movie visits Andrew will have enough points for a free movie.
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