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Hands of clock at 90 degrees

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August 11, 2019
Clock Problemsprmo 2k19

Problem Statement

On a clock, there are two instants between 1212 noon and 1 PM1 \,\mathrm{PM}, when the hour hand and the minute hannd are at right angles. The difference in minutes between these two instants is written as a+bca + \dfrac{b}{c}, where a,b,ca, b, c are positive integers, with b<cb < c and b/cb/c in the reduced form. What is the value of a+b+ca+b+c?