Final answer:
The units digit is 0, the hundreds digit is 4, and the tens digit is 8, making the 3-digit number 480.
Step-by-step explanation:
The question involves finding a 3-digit number where the hundreds digit is four more than the units digit, the tens digit is twice the hundreds digit, and the sum of the digits is 12. To solve this, we can use algebra.
Let's designate the units digit as 'u'. According to the problem, the hundreds digit will then be 'u + 4'. The tens digit is twice the hundreds digit, which gives us '2(u + 4) = 2u + 8'. Now we can use the information that the sum of the digits equals 12 to create the equation: u + (u + 4) + (2u + 8) = 12.
Simplifying this equation, we get: 4u + 12 = 12, which further reduces to 4u = 0. This indicates that u, the units digit, is 0. Thus, the hundreds digit is 0 + 4 = 4 and the tens digit is 2×4 = 8.
The 3-digit number we are looking for is therefore 480.