Çözüldü Inverse Proportionality

If 3 mail carriers of equal capacity deliver a certain amount of mail in 36 hours, how many hours would it take for 6 mail carriers with the same capabilities to deliver it?

3 mail carriers ===========> 36 hours
6 mail carriers ===========> x hours
6·x = 3·36
x = 18 hours.

Original Question (Turkish):
https://matematiknotu.com/wp-content/uploads/2020/05/Doğru-Ters-Bileşik-Orantı-Temel-Testi-1.pdf
(The last question, answers are at the bottom left of the same page.)