Question

Sonia opened a savings account and then added the same amount to the savings account every week. After 5 weeks, her savings account had a total of $45. After 10 weeks, her savings account had a total of $70. Which equation represents the amount of money (y), in dollars, in Sonia's savings account after x weeks?

Answer 1

First let's find the amount Sonia puts in her account each week.

To do so, let's find the amount increased between weeks 5 and 10:

`70-45=25`

The account increased $25 in 5 weeks, so for each week, we have:

`(25)/(5)=5`

So Sonia puts $5 in her account each week. Now, we need to find the initial value in the account. If after 5 weeks the account has $45, we can subtract $45 by 5 times the amount per week:

`45-5\cdot5=45-25=20`

So the initial amount is $20.

Now that we have the initial amount and the amount she puts per week, we have the following equation for the amount of money y after x weeks:

`y=5x+20_{}`

So the correct option is the third one.