I need to reverse a formula that was given to me in an equation.

The problem is..

For the following function,Ccomputes the cost in millions of dollars of implementing a city recycling project whenxpercent of the citizens participate.

The formula is

C(x) =1.5x

100 - x

I solved that...... now it says...

Using this model, estimate the percentage of participation that can be excepted if $5 million is spent on this recycling project? Set up an equation and solve algebraically. Round to the nearest whole percent.

I have no clue how to turn the equation around.

It's been 25 years since I took algebra in highschool and I'm expected to regurgitate it for College Algebra... can anyone atleast help me with setting up the formula?

Thanks in advance!!