I’m analyzing a rational function using derivatives and I’m having trouble with this one. Do I have to move on to the second derivative test if the first one does not equal zero?

The dance committee of pine bluff middle school earns $72 from a bake sale and will earn $4 for each ticket they sell to the spring fling dance. the dance will cost $400 write an inequality to determine the number, t of tickets the committee could sell to have money left over after they pay for this year's dance. what is the solution set of the inequality?