Question 923421
Please post as two separate questions. I'll answer # 1:
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s = 10 m/hr
m = 40 m/hr
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combined speed (aka closing speed) of Stephanie and Mom:
CS = s + m = 50 m/hr
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CS = distance/time 
50 = 10/time
time = 10/50
time = 1/5 hr
time = (1/5 hr) * (60 minutes/hr)
time = 12 minutes
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answer:
they meet at 3:12
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