6.
a)(2-1)/2 = 1/3
b)(9-7)/17 = 2/17
c)(7-3)/7 = 4/7
d)(4-2-1)/8 = 1/8
e)(9-1-11)/33 = (-3/33) = (-1/11)
f)(66-12-7)/20 = 47/20
7.
a)83/18 - 9/4 + 11/8 = (332-162+99)/72 = 269/72 = 3 întregi 53/72
b)(3+2-1+6)/6 = 10/6 = 5/3 = 1 întreg 2/3
c)2/5 + 4/3 - 11/15 = (6+20-11)/15 = 15/15 = 1
d)5/2 + 4/3 - 5/6 = (15+8-5)/6 = 18/6 = 3
