Brittany, Alex, and Jamy all share 600 marbles divided between them in the ratio 3:5:7. If Brittany gives Alex half of her marbles, what's the total number of marbles that Alex has? Give the rationale and then the answer.
Let's think step by step. The total ratio representing the number of marbles is 3 + 5 + 7 = 15. From the ratio, the fraction representing the number of marbles that Brittany has is 3 / 15, which is equal to 3 / 15 * 600 = 120 marbles. Alex has 5 / 15 * 600 = 200 marbles. If Brittany gives half of her marbles to Alex, Alex receives 1 / 2 * 120 = 60 marbles. After receiving 60 marbles from Brittany, Alex has 200 + 60 = 260 marbles.. The answer is: 260.

In a restaurant, a burger costs $9, and a pizza twice as much. How much would cost one pizza and three burgers? Give the rationale and then the answer.
Let's think step by step. One pizza costs twice as much as the burger, which means 9 * 2 = $18. Three burgers would cost 9 * 3 = $27. So one pizza and three burgers would cost in total 18 + 27 = $45.. The answer is: 45.

Diane is twice as old as her brother, Will. If Will was 4 years old 3 years ago, what will the sum of their ages be in 5 years? Give the rationale and then the answer.
Let's think step by step. Since Will was 4 years old 3 years ago, then he is 4 + 3 = 7 years old now. Dina is twice as old as he is so she is 2 * 7 = 14 years old now. In 5 years, Will will be 7 + 5 = 12 years old. In 5 years, Diane will be 14 + 5 = 19 years old. The sum of their ages at that time will be 12 + 19 = 31 years.. The answer is: 31.