Learn Turkish: Rekabet çok fazla olduğundan dolayı işletme iflas etti. - The business went bankrupt because there was too much competition.

It uses the causal structure from this lesson! We take ol (to be) and add -duğ (the fact that), -u (3rd person possessive), -n- (buffer), and -dan (ablative case). Literally it means "from its being." The word dolayı means "due to" and pairs with the ablative case.

Do I always have to use dolayı after the -dan ending?

No, it is optional. You could just say ...olduğundan işletme iflas etti and it would still mean "because there was too much competition." Adding dolayı just emphasizes the cause, similar to saying "due to the fact that" instead of just "because."

Why is there a 3rd person possessive -u on olduğundan?

In Turkish, subordinate clauses like this work like noun phrases. You are literally expressing "due to the competition's being too much." Since rekabet (competition) is the subject of this clause, we use the 3rd person possessive -u on the verb olmak to link the action to it.

What is the root of the word işletme (business)?

It comes from the verb işletmek, which means "to operate" or "to run" (a business, a machine, etc.). The -me suffix turns it into a noun. While it can mean the act of operating, it is the standard word for a "business" or "enterprise."