Final answer:
The first number is 5, the second number is three times the first, which makes it 15, and the third number is seven less than the second, which is 8. Their sum is 28. None of the options provided in the question matches the correct answer.
Step-by-step explanation:
We are given that the sum of three numbers is 28. Let us denote the first number as x. According to the problem, the second number is three times the first, so it will be 3x. The third number is seven less than the second, which gives us 3x - 7.
The equation based on the given information is:
x + 3x + (3x - 7) = 28
Simplifying, we have:
7x - 7 = 28
Adding 7 to both sides:
7x = 35
Dividing both sides by 7:
x = 5
Now, we can find the second and third numbers:
Second number: 3x = 3(5) = 15
Third number: 3x - 7 = 15 - 7 = 8
The three numbers are 5, 15, and 8, respectively, which is not an option given in the question. There may have been a mistake in the presented options.