Question 41169
Let's convert this word prolem into a mathematical expression:

Let the number be x.

Three times x is 3x.
If we decrease 3x by 8, it is 3x-8.

3x-8 is the same as twice the number, which is 2x, increased by 15, which is 2x+15.

So,
3x-8 = 2x+15
To solve the equation, move 2x to the left of the equation and -8 to the right of the equation.

3x-2x = 8+15
x = 23
The number is 23.