Question

the track coach tells Dave that he has 84% of his workout left. Dave has run 4 laps so far. How many laps will Dave run in all

Answer 1

If 4 is 100-84=16 % of his workout, 4 is 16/100 or 4/25 of his workout.  If 4=4x/25, where x is his workout length, dividing by 4 and multiplying by 25 gives x=25, so Dave must run 25 laps total.