Răspuns :
a) (11/45 - 1/30) x 18/19 amplifici 11/45 cu 2, 1/30 cu 3
(22/90 - 3/90) x 18/19 =
19/90 x 18/19 = 18/90 = 2/10 = 1/5
b) (11/12 - 7/15) x 10/9 + 1/2 amplifici 11/12 cu 5, 7/15 cu 4
(55/60 - 28/60) x 10/9 + 1/2 =
27/60 x 10/9 + 1/2 =
3/6 + 1/2 =
1/2 + 1/2 = 2/2 = 1