Explanation:
Create the column headings "Reactants" and "Products". The two row headings should be "Photosynthesis" and "Cellular respiration".
Before filling in the table, make sure you know what the products and reactants from photosynthesis and cellular respiration are.
Remember reactants are the 'before' on the left, and products are the 'after' on the right.
<u>Photosynthesis</u>:

<u>Cellular Respiration</u>:

See attachment for how the table could look.
A scientific law would be your answer.
There are many laws that are defined using formulas.
I hope this helps!
~cupcake
Silicates is the answer to this.