Question

sari has saved 1200. She borrowed 500 from her mother to purchase a laptop. Sari takes 25 out of her bank account each week to pay back her mother. Write the equation of the algebraic model of this situation. How many weeks until the account balance is 700$? and Is this an example of partial or direct variation?

Answer 1

The equation is:
`balance(n) = 1200 - 25*n`

It will take 20 weeks until her balance is $700. The problem describes a partial variation.

Explanation:

Since Sari takes $25 from her account for each week, then the balance on the account must be equal to the original money subtracted by 25 multiplied by the number of weeks that went by as shown below:

`balance(n) = 1200 - 25*n`

In order to find the number of weeks, n, that will take for the account to reach $700, we need to use this value on the left side and solve for n.

`700 = 1200 - 25*n\\25*n = 1200 - 700\\25*n = 500\\n = (500)/(25) = 20`

It will take 20 weeks. It is a partial variation, because the line doesn't pass through (0,0).