Writing and evaluating a function that models a real-world situation: advanced

ravi is putting money into a savings account. he starts with $350 in the savings account, and each week he adds $70.

let s represent the total amount of money in the savings account (in dollars), and let w represent the number of weeks ravi has been adding money. write an equation relating s to w. then use this equation to find the total amount of money in the savings account after 17 weeks.

equation: ?
total amount of money after 17 weeks: $?