$12$ crossings, $96$ dollars
Work Step by Step
Step 1. Assume $x$ crossings are needed. Step 2. Without the pass, the cost is $8x$ Step 3. With the pass, the cost is $36+5x$ Step 4. Letting $8x=36+5x$, we have $3x=36$ and $x=12$ and a total cost of $8(12)=96$ dollars per month for both.