Answer:
Explanation:
Let's call the three numbers we're trying to find "a", "b", and "c". We know that their sum is 3, so we can write:
a + b + c = 3
We also know that their difference is 21. However, we don't know if that difference is positive or negative, so we'll write two equations:
a - b - c = 21
b - a - c = 21
Now we have a system of three equations with three unknowns. We can solve for one variable in terms of the other two, and then substitute that expression into the other two equations to get a system of two equations with two unknowns. From there, we can solve for one variable and use that to find the other two.
Here's one way to solve the system:
a + b + c = 3
a - b - c = 21
b - a - c = 21
Adding the second and third equations, we get:
a - c = 42
Substituting this into the first equation, we get:
b + 42 = 3
b = -39
Substituting b and a - c into the second equation, we get:
a - (-39) - (a - c) = 21
a + 39 - a + c = 21
c = -18
Now we can find a by adding b and c to 3:
a = 3 - b - c
a = 3 - (-39) - (-18)
a = 24
So the three numbers are 24, -39, and -18, and their sum is 3 and their difference is 21.