Reviewing Supply & Demand for SAT & ACT

The quantity of pens supplied can be described as a function of price (p) such that s(p)=80+4p. The quantity of pens demanded can be described as a function of price(p) such that d(p)=100-12p. How do s(p) and d(p) differ? A market clears when supply equals demand. At what quantity and price does the market clear?