The situation would be that he answered incorrect 5 times assuming that he had 4 positive points to start off with
Probability of drawing a green = 4/13
Probability of drawing a red = 2/13
probability of drawing a green and then a red is 4/13 * 2/13 = 6/169
The equation would be
x - 18 = collection left
X = how much was your collection before you gave your brother 13 cards
Since we don't know how big was your collection before, this would be the equation to solve it.
Answer:

Step-by-step explanation:

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