Explanation

Let's define the ages of the three people:

• Let David's age be $D$.
• John's age is 4 years more than David's, so John's age is $D+4$.
• Joe's age is 2 years less than David's, so Joe's age is$D-2$.

The sum of their ages is given as 41:

$$(D)+(D+4)+(D-2)=41$$

1. Simplify the equation:

   $$D + D + 4 + D - 2 = 41$$ $$3D + 2 = 41$$

2. Subtract 2 from both sides:

   $$3D = 39$$

3. Divide both sides by 3:

   $$D = 13$$

So, David is 13 years old.

• John's age is $D + 4 = 13 + 4 = 17$ years.
• In 8 years, John's age will be: $$17 + 8 = 25 text{ years}$$