Question

Sam traveled 20 miles in 3 hours.

Sam walked part of the distance at a speed of 4 miles per hour.

Sam rode his bicycle for the remaining distance at a speed of 12 miles per hour.
note: this question has been asked before but i do not believe it was answered correctly, it was solved using 4 hours instead of 3

Answer 1

see below

Explanation:

distance / rate = time

x = walking distance 20 -x = biking distance

x / 4 m/hr + (20-x) / 12 m/hr = 3 hours

x/4 + ( 20-x) /12 = 3 multiply both sides of the equation by 12

3x + 20 -x = 36

2x = 16

x = 8 8 miles walking then 12 miles biking