Which function is the inverse of y= -3x + 6/7

If you shift the linear parent function, f(x)=x, up 13 units, what is the equation of the new function?

Which equation results from adding the equations in this system? x+6y=9 and -x+2y=-15

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