A group of people contains men, women, and children. The number of men is twice the number of women, and the number of women is 3 times the number of children. If the number of children is 30, how many people does this group contain?
Let's think: The number of women in the group is 3 women / child * 30 children = 90 women. The number of men in the group is 2 men / woman * 90 women = 180 men. The total number of people in the group is 180 men + 90 women + 30 children = 300 people.. The answer is: 300.

In a class of 30 students, the teacher polls the students on their favorite subject. 1/5 of the students like Math, and 1/3 like English. 1/7 of the remaining students like Science. The rest don't have a favorite subject. How many students don't have a favorite subject?
Let's think: 30 x 1 / 5 = 6 students like Math. 30 x 1 / 3 = 10 students like English. So, 6 + 10 = 16 students like either Math or English. Thus, 30 - 16 = 14 students neither like Math nor English. Since 1 / 7 of the remaining like Science, therefore 14 x 1 / 7 = 2 students like Science. Hence, 14 - 2 = 12 students neither likes the 3 subjects.. The answer is: 12.

Rick has just celebrated his 15th birthday. His oldest brother is twice his age, and his middle brother is a third of the oldest brother's age. The smallest brother is half the middle brother's age. If the youngest brother is 2 years younger than the smallest brother, how old, in years, is the youngest brother?
Let's think: Rick's oldest brother is 15 years * 2 = 30 years old. This means the middle brother is 30 years / 3 = 10 years old. The smallest brother is therefore 10 years / 2 = 5 years old. So the youngest brother is 5 years 2 years = 3 years old.. The answer is: 3.

Harry wants to build a homemade helium balloon with his son, Kevin, so he and Kevin go to the store with $200. They buy a giant sheet to turn into a balloon for $42, a rope for $18, and a propane tank and burner for $14. They plan to use the rest of the money on helium. The helium is $1.50 per ounce. For every ounce they buy, the balloon can fly 113 feet higher. How many feet up can they fly the balloon?
Let's think:
They have $126 for helium because 200 - 42 - 18 - 14 = 126. They can buy 84 ounces of helium because 126 / 1.5 = 84. They can fly 9,492 feet up because 84 x 113 = 9,492.. The answer is: 9492.