SOLUTION: Justin can run 10 km in the same amount of time that Leo can run 12 km. If Leo can run 1 kph faster than Justin, how fast can Leo run?

Algebra ->  Percentage-and-ratio-word-problems -> SOLUTION: Justin can run 10 km in the same amount of time that Leo can run 12 km. If Leo can run 1 kph faster than Justin, how fast can Leo run?      Log On


   

Question 1179938: Justin can run 10 km in the same amount of time that Leo can run 12 km. If Leo can run 1 kph faster than Justin, how fast can Leo run?
Found 2 solutions by ankor@dixie-net.com, MathTherapy:
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Let J = Justin's speed in km/hr
let L = Leo's speed
:
Justin can run 10 km in the same amount of time that Leo can run 12 km.
Write a time equation, time = dist/speed
j's time = L's time
10%2Fj = 12%2FL
cross multiply
12j = 10L
simpilfy, divide by 2
6j = 5L
:
If Leo can run 1 kph faster than Justin,
L = j + 1
or
j = L - 1
how fast can Leo run?
Replace j with (L-1) in the first equation
6(L-1) = 5L
6L - 6 = 5L
6L - 5L = 6
L = 6 km/h is Leo's speed
:

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!

Justin can run 10 km in the same amount of time that Leo can run 12 km. If Leo can run 1 kph faster than Justin, how fast can Leo run?
Let Leo's speed be S

Then Justin's is: S - 1

We then get the following TIME equation: matrix%281%2C3%2C+12%2FS%2C+%22=%22%2C+10%2F%28S+-+1%29%29

matrix%281%2C3%2C+6%2FS%2C+%22=%22%2C+5%2F%28S+-+1%29%29 ----- Factoring out GCF, 2, in NUMERATORS

5S = 6S - 6 ----- Cross-multiplying

5S - 6S = - 6

- S = - 6

Leo's speed, or