Answer
$38^\circ 32'$
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: $89^\circ 60'$
$89^\circ 60'-51^\circ 28'=(89-51)^\circ+(60-28)'=38^\circ 32'$
