4) Pentru ca fractia sa fie subunitara trebuie ca:
a)2x+3<x+7
2x-x<7-3
x<4
x∈{0,1,2,3}
b) 2x*100+(1+2+...+100)=5650
200x+100x101:2=5650
200x+5050=5650
200x=5650-5050
200x=600
x=600:200
x=3 verifica simultan conditiile de la punctele a) si b)
5) 333/222=(3x111)/(2x111)=3/2
