Please Help!!!!

Question

Drew and Adam leave home at the same time, traveling in opposite directions.  Drew drives 65 miles per hour and Adam drives 70 miles per hour.  In how many hours will they be 675 miles apart? 

Answer 1

Speed is the distance you cover in the corresponding time: v = d / t ⇒ d = v · t

Drew:

1. travels to the left at v_d = 65 mph
2. travels for t hours
3. covers distance d_d = v_d · t ⇒ d_d = 65 · t (Eq. 1)

Adam:

1. travels to the right at v_a = 70 mph
2. travels for t hours
3. covers distance d_a = v_a · t ⇒ d_a = 70 · t (Eq. 2)

Total final distance between Drew and Adam: d_a + d_d = 675 miles

(Eq 1) + (Eq 2): d_d + d_a = 65 · t + 70 · t ⇒ 675 = 135 · t ⇒ t = 5 hours

Answer 2

675/(65+70) = 675/135 = 5 hours

in 5 hours one goes 5x65 = 325 miles

in 5 hours the other goes 5x70= 350 miles

325+350 = 675 miles apart after 5 hours

distance = rate of speed times time

d=rt

675 =(65+70)x5 = 135x5