How can chemistry be used to solve a real world problem?

Idon’t know how to solve this question

An excess of lithium oxide undergoes a synthesis reaction with water to produce lithium hydroxide li2o+h2o→2lioh if 1.05 g of water reacted, what is the theoretical yield of lithium hydroxide? a) 5.83 x 10–2 g lioh b) 1.17 x 10–1 g lioh c) 2.79 x 100 g lioh d) 1.40 x 100 g lioh

Main expenses you plan on making payments on a new car too. you want to spend 15% of your monthly net pay on the car payment, insurance, registration, and taxes combined. what is your monthly car allowance? $149.46 $298.91 $448.37 $597.83