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Question 189082: I am learning about linear word problems, perpendicular lines, and horizontal and vertical lines for reviewing the chapter. This is the word problem: Jane got a regular job and started adding $9 per week to her savings account. At the end of 11 weeks, she had $315 in savings. Write a linear equation to model this situation. Identify the x- variable and the y-variable. The second question asks how much did she have in her account after the 4th week? I would really appreciate it if you could help me with this word problem. It would help me understand how to solve it. Thanks.
Answer by solver91311(24713)   (Show Source):
You can put this solution on YOUR website!
Since you want to know the value in the account after some number of weeks, it makes sense to write the function so that the function value is the amount in the account and the independent variable is the number of weeks.
So, let x represent the number of weeks. Since she is depositing $9 per week, 9x is the amount deposited in x weeks. The y value is the value of the function, in other words, the amount in the account.
Now, since we know that after 11 weeks she had $315 in the account (y = 315), and 11 weeks only accounts for $99 (11 X 9 = 99), she must have had $315 - 99 = $216 in her account when she started the job, so we know that when x = 0, y must equal 216.
Now we have enough to write the equation:
When x = 4,
 + 216 = 36 + 216 = $252)
John
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