The dance committee of pine bluff middle school earns $72 from a bake sale and will earn $4 for each

The dance committee of pine bluff middle school earns $72 from a bake sale and will earn $4 for each ticket sold they sell to the Spring Fling dance. The dance will cost $400

Let t be the number of tickets sold. We have a Revenue function R(t):
R(t) = 4t + 72

We want to know t such that R(t) = 400. So we set R(t) = 400:
4t + 72 = 400

Typing this equation into our search engine, we get:
t = 82