Derrick measures the length of his yard. The length of Alex's yard is half the size of Derrick's and the length of Brianne's yard is 6 times the size of Alex's. If Brianne's yard is 30 yards long, how long is Derrick's yard, in yards? Let's be accurate as possible.
The length of Alex's yard is 30 / 6 = 5 yards. The length of Derrick's yard is 5 * 2 = 10 yards.
The answer: 10.