Ess 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)

Let's consider that the number of people in the mall in that day was x

"Ess observed that 60% of the people at a mall on a particular day shopped for clothes" means


AND
"people at the mall did not shop for clothes that day" means 0.4x

So we got the equation:
" alt="0.6x=0.6(6250)=3750" /> " />

Hence we can calculate the number of the people who shopped for clothes:

So we can conclude that the number of people who shopped for clothes that day was 3750

Line ab is y = -7/5x + 56/5i don't understand  where point d comes into this.