Help it’s a test due in 10 mins

Plzzzz i beg u asap ! what is the equation of this graphed line? enter your answer in slope-intercept form in the box.

Can someone answer this question? : )

Jada has a meal in a restaurant she adds up the prices listed on the menu for everything they ordered and gets a subtotal of $42.00. when the check comes, it says they also need to pay $3.99 in sales tax. what percentage of the subtotal is the sales tax