SOLUTION: Kali left the White House and traveled toward the lake. Ndiba left one hour later traveling 15 mph faster in an effort to catch up to her. After two hours Ndiba finally caught up.

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Question 985093: Kali left the White House and traveled toward the lake. Ndiba left one hour later traveling 15 mph faster in an effort to catch up to her. After two hours Ndiba finally caught up. What was Kali's average speed?
The answer is 30 mph but I have no idea how to get there. Please help!
All I have so far is this:
n = k + 15
Is that even correct? Thank you!
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39620)   (Show Source): You can put this solution on YOUR website!
 
           speed     time     distance
Kali         r        t+1       d
Ndiba       r+15       t        d

After two hours, Ndiba caught-up. 


            speed     time       distance
Kali         r        2+1=3       d
Ndiba       r+15       2          d


Uniform Rates Rule for Travel, RT=D.
Answer by MathTherapy(10555)   (Show Source): You can put this solution on YOUR website!

Kali left the White House and traveled toward the lake. Ndiba left one hour later traveling 15 mph faster in an effort to catch up to her. After two hours Ndiba finally caught up. What was Kali's average speed?
The answer is 30 mph but I have no idea how to get there. Please help!
All I have so far is this:
n = k + 15
Is that even correct? Thank you!
What you have so far is Ndiba's speed, relative to Kali's, which is okay but you have to proceed

from there to solve for Kali's speed



Let Kali's average speed, be S

Then Ndiba's is: S + 15

Time taken for Ndiba to get to catch-up point: 2 hours

Time taken for Kali to get to catch-up point: 3 (2 + 1) hours

When Ndiba catches up to Kali, both would've travelled the same distance, and so, we get: 

3S = 2(S + 15)

3S = 2S + 30

3S - 2S = 30

S, or Kali' speed =  mph 

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