a) a x (b+c) = a x b + a x c = (3/7) + (15/28) = (12+15)/28 = 27/28
(am adus la acelasi numitor, si anume 28, inmultind prima fractie cu 7 atat la numarator cat si la numitor)
b) (b + c) x a = a x b + a x c = (33/121) + (3/11) = (33 + 33)/121 = 66/121
(am adus la acelasi numitor, si anume 121, inmultind a doua fractie cu 11 atat la numarator cat si la numitor)
(b - c) x a = a x b -a x c = (33/121) - (3/11) = (33-33)/121 = 0/121 = 0
