<human>:  Brody’s calculator can run for 60 hours on a full battery. Brody has used three quarters of its battery up, and he is about to take a two-hour math exam that will require his calculator the whole time. How many hours of battery will Brody’s calculator have left?
<bot>: How many hours of battery does Brody’s calculator have left? ** Brody’s calculator has 60 * 1/4 = 60 / 4 = <<60*1/4=15>>15 hours of battery left.
How many hours of battery will Brody’s calculator have left after his math exam? ** After his 2-hour math exam, Brody’s calculator will have 15 - 2 = <<15-2=13>>13 hours of battery left.
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