So the area is 2x3 cm with 68 paramecia.
Not sure if this is the best way to do it, but I’d do 68/2*3 (68 divided by (2 times 3))
So first 2*3 is 6cm.
Now you’re trying to find paramecia/cm2. You are trying to find a unit rate. That is a value over one.
Then because there are 68p and 6cm, to find the unit rate, you’d do 68/6.
Now you have your unit rate, which is 11.3 repeating, or 11 1/3 as a fraction.
That would be 11.3 (11 1/3) paramecia per cm2
also I’m not 100% sure if this is correct, just wanted to help, so no guarantees
