A factory begins emitting particulate matter into the atmosphere at 8am, algebra homework help

A factory begins emitting particulate matter into the atmosphere at 8am, algebra homework help

A factory begins emitting particulate matter into the atmosphere at 8am each workday, with the emissions continuing until 6pm. The level of pollutants, P ( t ), measured by a monitoring station ½ mile away is approximated as follows, where t  represents the number of hours since 8am. 

P(t)= {   75t+100  if 0 is less than or equal to t less than or equal to 4

   400   if 4 <t<8  

  -100t+1200  if 8 is less than or equal to t less than or equal to 10

  -50/7 t + 1900/7  if 10 <t<24

Find the level of pollution at 2pm and 5pm.