F
Pick an easy number for n, such as 10. If the average of four numbers is 10, the sum of the four numbers is 40 (4 × 10 = 40). If
three of the numbers are n + 3, n + 5, and n − 2, then those three numbers are 10 + 3, 10 + 5, and 10 − 2 or 13, 15, and 8.
Then 13 + 15 + 8 = 36. The sum of the four numbers must equal 40, so the remaining number is 4. If you plug 10 in for n in
each of the answer choices, only (F) gives you 4.vi.B
Start with the middle answer choice—9. If Mike has 9 shirts, then Adam has three times as many, or 27. If Adam gives Mike
6 shirts, Adam now has 21, and Mike has 15. This is not equal, so (C) is not correct. Since Adam was left with too many
shirts when Mike had 9, Mike must have fewer than 9. Try answer choice (B). If Mike has 6 shirts, then Adam has 18. If
Adam gives Mike 6, then they both have 12 shirts.vii.