Answer
$72^\circ 47'$
Work Step by Step
In this kind of subtraction, we subtract the degrees from the degrees and the minutes from the minutes:
$90^\circ$ can be rewritten as: $89^\circ 60'$
$89^\circ 60'-17^\circ 13'=(89-17)^\circ+(60-13)'=72^\circ 47'$
