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Old Apr 23rd 2017, 08:17 PM   #1
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AP Exam Booklet problem

My head is severely broken right now. Maybe I have never been taught this or I'm just an idiot and don't remember.

In the image that I clipped onto this thread I have a hard time understanding the last part where mb= (0.5kg) (7/3-1). Where does the -1 come from and why does it go in the parentheses with the 7/3. I understand how to get to (0.5kg)(7/3)=(0.5kg + mb) but how does that turn into the last part of the problem? Please I need help
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Last edited by DaveyBoySmith; Apr 23rd 2017 at 08:23 PM.
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Old Apr 24th 2017, 03:45 AM   #2
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Starting with:

0.5 kg (7/3) = 0.5 kg + mb

Subtract 0.5 kg from both sides:

0.5 kg (7/3) - 0.5 Kg = 0.5 kg + mb - 0.5 kg

0.5 kg (7/3) - 0.5 kg = mb

Now apply the distributive property to the left hand side; recall that a(b+c) = ab + ac. In this case a =0.5 kg, b= 7/3, and c= -1:

0.5 kg (7/3) - 0.5 kg = 0.5 kg (7/3) + 0.5 kg (-1) = 0.5 kg (7/3-1)

Hence

0.5 kg(7/3-1) = mb
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