Answer:
![12\ weeks](https://img.qammunity.org/2021/formulas/mathematics/middle-school/cca5e39i5hu3yoktqfdaigyr9ygja5nfp0.png)
Explanation:
The complete question is
Angelo recently opened a bank account and deposits the same amount each week. After 8 weeks, he deposited $280. He wants to deposit a total of 420 in his account. How many weeks will it Angelo to deposit a total of $420
we know that
A relationship between two variables, x, and y, represent a proportional variation if it can be expressed in the form
or
![y=kx](https://img.qammunity.org/2021/formulas/mathematics/middle-school/15ggalazf8cpjag5fv34y8ftpnv14l6oxo.png)
Let
x ----> the number of weeks
y ----> the total deposit in the bank account
In this problem we have a proportional relationship between the variables x, and y.
we have the ordered pair (8,280)
Find the constant of proportionality k or slope of the linear equation
![k=(280)/(8)=\$35\ per\ week](https://img.qammunity.org/2021/formulas/mathematics/middle-school/vluql2k4poqveivdjbt89gi25romgpa9mt.png)
so
The linear equation is
![y=35x](https://img.qammunity.org/2021/formulas/mathematics/middle-school/o6w2eekqqud4evak7l7j8nb1d68aw5dy6d.png)
For y=420
Substitute in the linear equation
![420=35x](https://img.qammunity.org/2021/formulas/mathematics/middle-school/9q81jix1k5z5vmu0qw0g47lp47f6tu2t4a.png)
Solve for x
![x=12\ weeks](https://img.qammunity.org/2021/formulas/mathematics/middle-school/vm2bs0a9unt7bchjmof90h8nx4rn7si21f.png)