The demand for snoofs is found to be Q = 1000 – 12Ps – 5Pt + 0.4Y, where Ps is t

The demand for snoofs is found to be Q = 1000 – 12Ps – 5Pt + 0.4Y, where Ps is the price of snoofs in dollars , Pt is the price of toofs in dollars, Y is income in thousands of dollars and Q is quantity of snoofs in thousands. Currently, Ps =40, Pt = 30, and Y=30. If the Snoof Company wanted to maximize REVENUE, what price would they set? Please use up to two places after the decimal in your calculations.
$71.80
$43.40
$40.00
$35.90
What is the answer to this? I thought it was $40, but I am not sure where to go after multiplying each factor (12×40, 5×30, .4X30)?