Question

train traveling north @ 60mph. one hour later, another train leaves @ 70mph. how far away before second train catches up? t

Answer 1

right so this is a bit harder to parse

Answer 2

so basically the second train has caught up once the distances they've traveled are exactly equal

Answer 3

ok so in one hour, once the second train leaves, the first train has a 60mph*1hr head start

Answer 4

so it's gone exactly 60 miles already

Answer 5

so from that point on, we're basically solving for some time T

Answer 6

70*T - 60*T = 60 (the head start being 60mph)

Answer 7

or in time T, when they have traveled the same distance, we know that 70*T = 60 + 60T

Answer 8

so 70T - 60T = 60 = 10T

Answer 9

so 10T = 60

Answer 10

In six hours, they would have traveled the same distance

Answer 11

so now let's check this:

Answer 12

In 6 hours from the original 1 hour, the first train has traveled 7hours

Answer 13

so it's traveled 7 hours * 60mp/h = 420 miles

Answer 14

the second train has traveled 6 hours total. so 6 hours * 70mph = 420miles

Answer 15

which is exactly the point the second train passes the first

Answer 16

make sense?

Answer 17

yep!!

Answer 18

awesome =)