I don't know if I'm approaching this, but I'll give it a shot.
Total weight of mixture = 1.8 + 1.38 = 3.18g.
% of aspirin = 1.8/3.18 * 100 = 56.25%
56.25% of 0.32g = 0.18g of aspirin
=> No. of moles of aspirin = no. of moles of salclicylic acid = 0.18/180 ~= 0.001mol.