b=p-3 (bill ran 3 mins faster than peter, so peter's time minus 3 equals bill's time)
-->p=b+3 (solve for p)
m=b/3 (michael was 3 times quicker than bill, so if you take bill's time and divide it by 3 you get michael's)
b+p+m=24 (the three equal 24)
b+(b+3)+(b/3)=24 (solve for b)
3b/3 + (3b+9)/3 + b/3 = 72/3 (find common denominator)
(4b + 3b + 9)/3 = 72/3 (combine)
7b+9=72 (multiply both sides by 3 to get rid of fraction)
7b=63
