For 109percent labelled oleum if the no. of moles of H2SO4 and free S03 be x and y resp. then whay will be the approx value of x+y/x-y (here / means division)

Answer 1

If I understand the question correctly, H2SO4 is about 98% which makes SO3 about 11%.
So (x+y) = about 109
(x-y) = about 87
(x+y)/(x-y) = about 109/87 = ?

Answer 2

109 % oleum contain 9 g of H2O, 40 g of SO3 and 60 g of H2SO4.Number of moles of free H2SO4 =x =Mass Molar mass=6098Number of moles of free SO3 =y=Mass Molar mass=4080Now, x+yx−y =6098+40806098−4080 =9.9 9.9 is correct answer