Ireally need to know how long it takes the large pipe on its own

s = hours it takes the small pipe on its own.

L = hours it takes the large pipe on its own.

we know the small pipe can do it in 11 hours total, so s = 11, so, how much of the whole job has the small done in 1 hour only?

well, if it takes 11 hours to do the whole thing, in 1 hour it has done only 1/11 of the whole job.

we know both pipes working together can do it in 6 hours flat. So in 1 hour only, both of them have done only 1/6 of the whole thing.

in that 1 hour, how much has the large one done? well, it has only done 1/L of the job.

and you can round that up as needed.

this may not be at all, but i use the same website you're using for school, and if i'm stuck doing one of these i try to look for it on the section.