The sun of a certain number and 3 times the number is 40. What is the number?

Let x = the unknown number.

x + 3x = 40
4x = 40
x = ?

To find the number, we need to set up an equation based on the given information.

Let's assume the number is "x". According to the problem, the sum of the number and 3 times the number is equal to 40. Mathematically, we can represent this as:

x + 3x = 40

Combining like terms, we have:

4x = 40

To isolate x, we divide both sides of the equation by 4:

4x/4 = 40/4
x = 10

Therefore, the number is 10.