A group of friends orders 5 pizzas for a party. Each pizza is cut into 8 slices. If they have eaten 17 1/2 slices so far, how many more slices are left for the group to share?

The total number of slices for the 5 pizzas is 5 x 8 = <<5*8=40>>40.

The number of slices that are left for the group to share is 40 - 17 1/2 = <<40-17=23>>23 slices. Answer: \boxed{23}.