Posted by Ashley on .
At the beginning of the summer molly decided to add a little money into her sayings account every week. After seven weeks her account had $175. At the end of 15 weeks her account had $375. Assume that she put the same amount of money into her account every week and will continue to do so.

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Steve,
Sounds like a good plan.
Was there a question in there somewhere? 
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Ashley,
I was trying to find the expression for the problem

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Ashley,
I have to find the equation of the line, but I need the expression to solve it.

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Steve,
looking at the data, it appears she saved #25 each week. So, after x weeks, her saving y would be
y = 25x
You can work into that by noting that if
y = mx+b
when x=7,
175 = 7m+b
when x=15,
375 = 15m+b
so, 8m = 200
m = 25
Now you have
y = 25x+b
plugging either point shows that b=0, so
y = 25x 
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Ashley,
How much was in her account four weeks after she began saving?

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Ashley,
Oops wrong question
I meant to ask
When she started saving money, 203 shopping days were left until Christmas. How much money was in her account at Christmas? 
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Steve,
well, you have the equation. How many weeks from the time she started saving, until Christmas? $25/week, babe.
I assume you know how many days per week . . . 
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Ashley,
Thank you I got it....so helpful

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Christy,
I have that same question but every time I try to put the expression it says it's wrong can you please tell me the expression you used??