nevermind i think i got it
Determine the tax t per unit that must be imposed to obtain the maximum tax revenue. (Hint: Use the solution of output as a function of t from 2(b) to formulate the tax revenue function.)
So output was originally and cost was
I worked out what the profit maximising value of x was and substituted it in .
thus
But im not sure what I do to formulate the tax revenue function.