math
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.

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

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

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 
How much was in her account four weeks after she began saving?

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? 
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 . . . 
Thank you I got it....so helpful

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??