How can I solve h-17=-12

So, to solve for H,
you need to undo the problem.
so since 17 is being subtracted,
you do the opposite if subtract
and add 17 to -12
so, 17+ (-12)= 5
To conclude H= 5
to check your answer add the 5 to replace the H
5-17=-12

The answer is 225 miles per 4.5 hours. hope this ; )