Using the lithium oxide and water as an example, look at the coefficients before each chemical (if none, assume a 1) and create a ratio of the reactant you need to find over he product, or vice versa, and then using proportions set up a fraction with the given moles and solve the proportion. For the answer to the lithium question is 1.1 moles since the ratio of lithium oxide to lithium hydroxide is 1:2