a) 10/1 * 3/2 * 3/2 = 90/4 = 45/2 = 22,5
b) 20 - 27/4 : 9/2 = 20 - 27/4 * 2/9 = 20 - 3/2 = 20 - 1 1/2 = 18 1/2
c) 2/3 * 120 = 240/3 = 80
:)
