9 b. a+a+1+a+2=63
3a=63-3=60, a=60/3=20
aldoilea numar=a+1=20+1=21
al treilea numar=a+2=20+2=22
produsul celor trei numere=20x21x22=9240
9c. x= nr de pagini
x=2x/4+x/4+30, numitor comun 4
4x=2x+x+120
x=120 pagini
2x/4=240/4=60, folosim regula de trei simpla
120p......100%
60p...........x%
x=60*100/120=50%
x/4=120/4=30pagini
120p........100%
30p.............x%
x=30*100/120=25%
