"20 miles in 1/2 hour" is a speed, or rate
(20 miles) per (1/2 hour)
(20 miles) / (1/2 hour)
(20 miles) * (2/(1 hour)) [to divide by fraction, invert and multiply
(20*2) miles/hour
40 miles/hour
40 miles per hour
(30 miles) per (3/4 hour)
(30 miles) / (3/4 hour)
(30 miles) * (4 / (3 hours) )
(30*4/3) miles/hour
40 miles/hour
40 miles per hour
Same speed (or rate).
