A table has 4 sides since they are rectangles let's assume that two sides can fit 2 chairs and two sides can fit 1. That's 6 total, now if you put ten end to end, eight tables ends are completely cover (16 chairs are taken out of the equation), then the end tables have one end covered on each side (-2). There are now 18 chairs gone. He can only fit (60-18= 42) 42 chairs on the tables.
