There were four pears (2 pairs) on the tree. The first man took a pair (2 pears) and the second only took one pear leaving one pear on the tree.

The answer is 87, in order to solve this you need to look at the numbers upside down. The sequence comes out to be 86, ?, 88, 89, 90, 91; therefore the ? is 87.

The dark.