Or, is it asking you to subtract the? In that case
5/4 - 3/8 = 7/8
So your friend bought 1 set of brush and 5 bottles of paint
you bought 2 brushes and 7 bottles of paint
1 bottle=3.69
friends cost+your cost=51.69
total you bought 3 brushes and 12 bottles
each bottle is 3.69
12*3.69=44.28
totalcost=51.69=3brushes+12bottles
51.69=3brushes+44.28
minus 44.28 from both sides
7.41=3brushes
divide both sides by 3
2.47=1brush
1 set of paint brushes=$2.47
First you would set up the problem as a division problem

and you would get the answer of
9 minutes and 37 seconds.
This answer to this question is 32.