Each of the three oldest children sleeps in a twin bed. they all need bed sheets. a brand of sheets is on sale for "but one get one at 50% off".if each sheet costs $18.00, how much will two sheets cost? how much will six sheets cost?

50% of 18 = 9

 so buy 1 for 18 and 1 for 9 = 18+9 = 27 for 2 sheets

6/2=3

27 x 3 = 81 for 6 sheets

fist on the left goes with the third on the right. second on the left goes with the fourth on the right. third on the left goes with the second on the right. the fourth on the left goes with first on the right