Answer: The number is -4.
Explanation:
To find the number, let's translate the given problem into an equation. We are told that "Eight decreased by three times a number is 20."
1. "Eight decreased by three times a number" can be written as 8 - 3x, where x represents the unknown number.
2. According to the problem, this expression is equal to 20. So we can write the equation as 8 - 3x = 20.
To solve for x, we need to isolate the variable. We can do this by performing inverse operations.
3. First, let's move the constant term (8) to the other side of the equation by subtracting 8 from both sides:
8 - 3x - 8 = 20 - 8
-3x = 12
4. Next, we divide both sides of the equation by -3 to isolate x:
(-3x)/-3 = 12/-3
x = -4
Therefore, The number is -4.