Fie a,b,c numarul de pagini din cele trei carti
a-75a/100=25a/100
b-80b/100=20b/100
25a/100=20b/100=c/3
a/4=b/5=c/3=(a+b+c)/(4+5+3)=3000/12=250
a=4x250=1000
b=5x250=1250
c=3x250=750
n=numarul de pagini citite pe zi
(750/n)x100/(1250/n)=750/nxn/1250x100=3/5x100=60%