Help meh please! : )

Use the inverse of the function y=x^2-18x to find the unknown value [tex]y = \sqrt{bx + c \: + d} [/tex]

Ahigh definition tv cost $800 with a down payment of 2/5 of the cost. how much is left to pay, in dollars after the down payment has been made?

Judy garland electronics operate on a net-profile rate of 20% on its printer cables. if the markup is $8.95 and the overhead is $4.31,find the net profit and the selling price? use the net-profit rate formula to solve this problem.