As noted above, the question is badly phrased. What the teacher probably meant to ask is “How many days will 1 turkey take to lay 1 egg?” (I see on preview that moriah beat me to this rephrasing.)
In that case, you don’t want to disregard the number of turkeys, but the time instead. We have 100 turkeys laying 10,000 eggs in <some time>, so how many eggs does 1 turkey lay in <some time>? 10,000/100 = 100 eggs. Since <some time> = 100 days, we have 1 egg per day.
(This problem is an old standard, though it usually involves the rate of digging ditches or laying bricks. The usual solution is to set aside the value you’re looking for while you simplify the others as I did above.)