Laminar starts with $350 in the savings account, and
Each week he adds $70.
One week

Two weeks

Therefore, w weeks

The equation relating S, which is the total amount of money in the savings account, and W, which is the number of weeks will be the original money plus the added money.

Then the equation to find the total amount of money in the savings account after 13 weeks is

Therefore, the total amount of money in the savings account after 13 weeks is
$1260.
The equation is,
