Question

Jess observed that 60% of the people at a mall on a particular day shopped for clothes. If 2500 people at the mall did not shop for clothes that day, the number of people who shopped for clothes that day was _______. (only put numeric values, no other symbols)

Answer 1

If 60% is shopping, then 40% is not shopping (100% - 60%=40%). You can use a cross-multiplication, or the rule of three for the equivalences, I mean:
2500/40% = x/60% so you solve for x and get x = 60%*2500/40% = 3750 people who shopped that day.