Question

Once you've identified the initial and final conditions, you're ready to solve for the unknown quantity in your problem. Boyle's Law expresses the pressure-volume relationship as P Vi = BV2, so you will need to solve this equation for the unknown quantity and then plug in your known values to calculate the unknown. What pressure would it take to compress 300. L of helium gas initially at 1.00 atm into a 2.00 L tank at constant temperature

Answer 1

First you made a typo. You should have written P1V1 = P2V2
Second, I don't understand your problem. All you need to do is to substitute the values in the problem and solve the equation. Here goes.
P1V1 = P2V2
P1 = 1 atm
V1 = 300 L He gas
P2 = unknown pressure in atm. Solve for this.
V2 = 2 L
Plug those values in and solve for P2
P2 = ?
Post your work if you get stuck.