Suppose the supply and demand for a certain textbook are given by supply: p = 1/2 q^2, demand:

Hi! I'm working on the following problem and would like some help: Suppose the supply and demand for a certain textbook are given by supply: p = 1/2 q^2, demand: p = - 1/2 q^2 + 20, where p is the price and q is the quantity. Find the demand quantity and the supply quantity at a price of $10.