19) 38.75 miles
62*.625(aka 5/8) =38.75
20) x = -4 / x = +4
X^2 + 1 = 17 >subtract 1 from both sides.>X^2 = 16. both -4 and +4 squared equal +16.
21)
With 6 pints for 1.92, each pint is worth .32
With 4 pints for 1.26, each pint is worth .315
The smaller bottle has a smaller pint to cost ratio allowing for same item but at a smaller cost. If the 4 pints are bought, one saves a total of .02.