Answer
$80$
Work Step by Step
Step 1. Assume there are $x$ passengers in exceeding of $75$, the total number of passengers would be $x+75$
Step 2. The price for each passenger would be $225-5x=5(45-x)$
Step 3. The revenue would be $R=5(45-x)(x+75)=5(3375-30x-x^2)$
Step 4. Let $R=16,000$, we have $5(3375-30x-x^2)=16,000$ or $3375-30x-x^2=3,200$ resulting $x^2+30x-175=0$
Step 5. Factor to get $(x-5)(x+35)=0$, thus $x=5$ and the total number of passengers is $x+75=80$
