Answer:it all take them 0.8 hours
Explanation:
Let x represent the distance covered by Fed.
Their houses are 4 miles apart. It means that by the time they meet, John would have covered 4- x miles.
Let t represent the time taken by Fred to cover x miles and also the time taken by John to cover 4 - x miles.
Distance = speed × time
Therefore,
Distance covered by Fred would be
x = 3 × t = 3t
Distance covered by John would be
4 - x = 2 × t = 2t
Substituting x = 3t into 4 - x = 2t, it becomes
4 - 3t = 2t
2t + 3t = 4
5t = 4
t = 4/5 = 0.8 hours