You need to put the given amount first to solve it: 150L O2 then 1 mol of known(O2)/22.4L then you put the mol ratio (B/A) in this case it is 3CO2/5O2 then 22.4L/1 mol of unknown (CO2) the answer after multiplying and dividing is 90L CO2.
If you don’t have that sheet that i put over the problem search it like formula of stoichiometry it will help you a-lot and good luck put attention
