a. a+b+c=3000
a-75%a=b-80%b=c-2/3c=k
25/100*a=20/100*b=1/3*c=k
a=4k, b=5k, c=3k
4k+5k+3k=3000
12k=3000
k=250
a=1000 pag, b=5*250=1250 pag, c=3*250=750 pag
b. 1250 pagini are al doilea volum
750 pagini are al treilea volum
750/1250=75/125=3/4
Procentul este 3/4*100=75%