Explanation:
42 1/3 miles per 1 1/3 hour.
42 1/3 = 127/3 miles.
1 1/3 = 4/3 hours.
to bring it back to 1 hour per the requested norm of miles per hour, we need to find the factor to multiply 4/3 with to get 1 :
4/3 × x = 1
4x = 3
x = 3/4
to keep the ratio value itself unchanged, we need to multiply also the numerator (top) of the ratio (or fraction) by 3/4.
127/3 × 3/4 = 127/4 = 124/4 + 3/4 =
= 31 3/4 =31.75 miles / hour
he drove 31.75 (or 31 3/4) miles in 1 hour.