You are measuring primary production of a seawater sample using the Light-Dark bottle O2 method

You are measuring primary production of a seawater sample using the Light-Dark bottle O2 method. The data you get for O2 concentrations are as follows. Remember, both the light and dark bottles contain respiratory activities of autotrophs and heterotrophs.
Time (h) O2 (µM)
0 220
24 260 (Light Bottle)
24 204 (Dark Bottle)
a. What is the value of net community production (µM O2 /hr)? Would this sample be a source or sink of CO2?
b. What is the value of community respiration (phytoplankton + heterotrophic respiration (µM O2 /hr)?
c. Calculate Gross Primary Production (µM O2 /hr).