I'm assuming you mean

we can factor that sum of perfect cubes from

into

so therefor

that is simpliest form
Try to find the best domnatior and then do the mixed number then simplify
(1/5) / 4.5 = 2 / m....1/5 mile to 4.5 minutes = 2 miles to m minutes
cross multiply
(1/5)(m) = (2)(4.5)
1/5m = 9
m = 9 * 5/1
m = 45 minutes <===
SOLUTION
At the same time t,
Train 1 would have covered a distance of 80t, since distance = average speed x time.
Train 2 would have covered a distance of 70t.
Now both added should give 210 miles
That is 80t + 70t = 210
150t = 210
t = 210/150
t = 1.4 hours
5. 60/12 is 5 :) hope this helps