[Question]: During a unit on probability, a teacher surveys her class asking her students two questions. The first question was whether they prefer dogs or cats, and the second question was whether they movies or video games. Of the 30 students in her class, 50% chose dogs and video games as their two answers, while 10% chose dogs and movies as their two answers. In total, how many students in this teacher's class prefer dogs over cats?
[Answer]: The 50% of the class that chose dogs and video games amounts to 30 * 0.5 = 15 students who prefer dogs over cats. Similarly, the 10% that chose dogs and movies amount to 30 * 0.1 = 3 students who prefer dogs over cats. Because these are the only two ways that a student could indicate their preference for dogs, and because these groups do not overlap, a total of 15 + 3 = 18 students favor dogs over cats in this teacher's class.
So the answer is 18.

[Question]: Randy had $3,000. Smith gave him another $200. Randy then gave Sally $1,200 and kept the rest. What was the value, in dollars, of the rest?
[Answer]: After Smith gave him $200, Randy had 3000 + 200 = 3200 dollars. The value of the rest of the money is 3200 - 1200 = 2000 dollars.
So the answer is 2000.

[Question]: Jonas is trying to expand his wardrobe. He has 20 pairs of socks, 5 pairs of shoes, 10 pairs of pants and 10 t-shirts. How many pairs of socks does he need to buy to double the number of individual items in his wardrobe?
[Answer]:
First, we must recognize that all pairs of shoes and socks are actually two items each, whereas the pants and the t - shirts are individual items. Therefore there are 20 * 2 = 40 individual socks in 20 pairs of socks. Similarly, there are 5 * 2 = 10 individual shoes in 5 pairs of shoes. Therefore, Jonas has 40 + 10 + 10 + 10 = 70 individual items in his collection. To double this number, we perform 70 * 2 = 140. This means we need 140 - 70 = 70 new items to double the size. Since there are 2 individual socks in each pair, we take 70 / 2 = 35 new pairs of socks.
So the answer is 35.