n=m/M=780/78=10 kmoli C6H6
x.................x..............................x
C6H6 + CH2=CH2 ===> C6H5-CH2-CH3
y...................2y............................y
C6H6 + 2CH2=CH2 ===> C6H4-(CH2-CH3)2
z......................z
C6H6 ===> C6H6
x/y=5/0,5 =>y=0,5x/5 => y=0,5*7,6923/5=0,76923 kmoli dietilbenzen
x/z=5/1=>z=x/5 => z=7,6923/5=1,53846 kmoli C6H6
x+0,5x/5+x/5 = 10 => 6,5x/5=10 => x=50/6,5=7,6923 kmoli etilbenzen
R: b) 7,69 kmoli etilbenzen