So if boys is 6 and girls is 15 it would be 6/15, but that can be simplified to 2/5.
% Increase = Increase/original number x 100
Let I represent increase
((58-32)/32) x 100 = I
58oz - 32oz = 26oz
26/32 x 100 = I
0.8125 x 100 = I
Increase = 81.25%
Move -4 to the other side
7x=24+4
7x=28
x=4
Whats the question? or any specific information