We assume the unit rate of interest is dollars per pound. To find that, we divide the number of dollars by the number of pounds. ("Per" essentially means "divided by.")
$2.49/(5 lb) = (2.49/5) $/lb ≈ $0.50/lb
_____
pounds per dollar is also a unit rate. That one would be
400 pages in 5 days but 120 on the first day so 400-120=280 280 is what he read in the 4 days following so divide 280 equally among the 4 days You get 70 per day after the first
