Please answer values!! 30 pts

Consider the function f(x)=-5x+3 what is f(-2)

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

Solve each quadratic equation by factoring and using the zero product property. n^2 - 49 = 0