Răspuns:
a) (7/8 - 1/8) + 1/4 = 6/8 + 1/4 = 3/4 + 1/4 = 4/4 =1
b) (5/6+7/6)-1/7= 12/6-1/7 = 2/1-1/7 = 14/7 - 1/7 = 12/7
c) (7/3 - 4/3)-12/13 = 3/3 - 12/13 = 1/1 - 12/13 = 13/13 - 12/13 = 1/13
d) 4/3-(9/11+2/11)=4/3-7/11=44/33-21/33 = 23/33
