please help me!
roland had already covered 14km when charlemagne headed out to catch him. Charlemagne's rate was 11kph, whereas Roland's rate was 7 1/2kph. How long did it take Charlemagne to catch Roland?

Question

please help me!
roland had already covered 14km when charlemagne headed out to catch him. Charlemagne's rate was 11kph, whereas Roland's rate was 7  1/2kph. How long did it take Charlemagne to catch Roland?

whpalmer4 · Answer

Charlemagne's speed is 11 km/h, Roland's is 7.5 km/h.  That means that Charlemagne gains (11 - 7.5) km/h = 3.5 km/h on Roland.  If Roland has a head start of 14 km, we just need to divide 14 km by 3.5 km/h to find out how many hours it takes to catch up.

Another way of looking at this is that Charlemagne's position at time t is 11t, and Roland's position is 14 + 7.5t.  We set the two of them equal to each other and solve for t.

11t = 14 + 7.5t
3.5t = 14
t = 14/3.5 at the time they have both traveled the same distance.

anonymous · Answer

so the answer is 4h?

whpalmer4 · Answer

Yep, 14/3.5 = 4 in my experience, your mileage may vary :-)