What is x = too?pls help

Aline passes through 3,7 and 6,9 what equation represents the line

Sally deposited money into a savings account paying 4% simple interest per year.the first year,she earn $75 in interest.how much interest will she earn during the following year?

At your job you're paid $50 per week plus $3 per sale at least how many saled do you need to make in order to have over $250