3
a) -3 + 5:(-5) = -3 -1 = -4
b) (-6) * (-15 +12) = (-6) * (-3) = 18
4
a) 8:2/5 = 8 * 5/2 = 20
b) 4/9:5/3 = 4/9 * 3/5 = [tex]\frac{4}{15\\}[/tex]
c) 5 * 7:5/8 = 5 * 7 * 8/5 = 56
