When trying to calculate the probability of a sequence of events you need to multiply the probability of the first event happening by the probability of the second event happening. There are a total of 4 numbers (2,3,4,5) and only one is a 2. Therefore the probability of the first pick being a 2 is 1/4. Now there are only 3 cards left (3,4,5) and only 2 numbers are greater than 3 so the probability of picking one of these cards is 2/3. Now that we have both of these probabilities we simply multiply them together.
1/4 * 2/3 = 2/12 or 1/6
Therefore, the probability of picking a 2 and then picking a number greater than 3 is 1/6
Theo got an 80% on the quiz because you multiply to get a equivalent fraction since a hundred is a whole of a percent. So basically, the percent is 80% and the decimal is 0.80.