c. Both options A and B will allow him to meet his goal.
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On his original plan, he is $30 short. (A) By delaying his class 1 week, he can add one more payment, so will have $95 more than he needs. (B) By increasing his payment $15 each week for the remaining 2 weeks, he will have exactly the amount he needs to take the class at the time he originally wanted.