Expert: Paul Klarreich - 10/3/2010

Question
mary leaves her house at noon, traveling in her car st 45mh. later, mary's brother joe leaves their house and travels in the same direction at 60mph. if joe leaves two hours later than mary does, what time will he catch up to her?

Answer
Questioner:   Ellen
Category:  Calculus
Private:  Yes  << don't do this.
 
Subject:  please help before tomorrow, 10/04/10
Question:  mary leaves her house at noon, traveling in her car st 45mh. later, mary's brother joe leaves their house and travels in the same direction at 60mph. if joe leaves two hours later than mary does, what time will he catch up to her?
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Let:

t = the elapsed time driven by Mary until Joe catches up with her.

Then:

t-2 = the elapsed time driven by Joe until he catches up with her.

And:

The distance traveled by Mary is [you fill in]

The distance traveled by Joe is [you fill in]

And finally:

Those distances are the same,

So:

You will write and solve an equation for t, and
You will interpret it in terms of the conditions.

And finally:

You will send these problems to the BASIC ALGEBRA section, not calculus.