a) ( x/2 +x/3 +x/6) - ( 1/2 *x + 1/3*x +1/6*x)=
= x/2+x/3+x/6- 1*x/2 -1*x/3- 1*x/6=
Deoarece 1 inmultit (*) cu orice numar da numarul respectiv
=> x/2+x/3+x/6-x/2-x/3-x/6=0
c) x/3+2x/5-4x/10+7x/3-x+x/3
Aducam la aceeasi baza care este 30
=> x/3*10/10 + 2x/5*6/6-4x/10*3/3+ 7x/3*10/10- x* 30/30 + x/3* 10/10
= 10x/30+ 12x/30-12x/30 + 70x/30-30x/30+ 10x/30
Baza se anumeaza deoarece este aceeasi
=> 10x+12x-12x+70x-30x+10x= 60x