If you have worked out the MOLES of two reactants then the limiting reagent is the one with less moles. Sorted? Well, it depends. If the reactants are in a 1:1 ratio then the above is true. But if the ratio is not equal then I'm afraid it's a bit more complicated. Let's say reactants A and B have a ratio of 2:1 in the balanced equation. If we have 0.02 moles of A and 0.015 moles of B which is the limiting reagent? If we start with A we can see from the ratio that 0.02 moles