Answer:
t = 4 hours
Explanation:
The distance is the same. The formula for distance is d = r*t
You could find the distance from the return trip. I'll do it that way and then take the short cut.
Method One
r = 60 km / hr
t = 5 hours
d = ?
d = r * t
d = 60 km/ hr * 5 hr The hours cancel.
d = 300 km
Now the faster trip
d = 300 km
r = 75 km
t = ??
d = r * t
300 = 75 * t Divide both sides by 75
300/75 = t
t = 4 hours.
Method Two
The distance is the same in both cases
r1 * t1 = r2 * t2
r1 = 75 km/ hr
t1 = ??
r2 = 60 km / hr
t2 = 5 hours
r1 * t1 = r2 * t2
75 * t1 = 60 * 5
75 km/hr * t1 = 60 km/hr * 5 hr
75 km / hr *t1 = 300 km Divide by 75
t1 = 300 / 75
t1 = 4 hours
Notice both methods give the same answer.