Answer:
34
Explanation:
We actually don't care what amount of paper is white, we just need the amount per truck. If there were 2 trucks, they would each take half of the total amount of paper. If there were 3 trucks, they would each take a third of the total amount of paper. And so on for 4,5,6,etc.
For 28 trucks, they would each take a twenty-eighth of the total amount of paper. So, the amount each truck takes is just
.
So, the answer is
and we're done!