Kevin is 39 years old and Daniel is 3 years old. How many years will it take until Kevin is only 4 times as old as Daniel?

Answer 1

Let's create an equation to solve this problem.

Let x represent the number of years that will need to pass. To represent Kevin's age, we'll use the expression 39 + x and to represent 4 times Daniel's age, we'll use the expression 4(3 + x).

In words, this equation can be represented as "Kevin's age plus x years is equal to four times Daniel's age plus x years." This is exactly what we need, since we need to know how many years will pass until Kevin's age is equal to four times Daniel's age.

Since Daniel's age needs to be equal to 4 times Daniel's age, set the expressions equal to each other:

39 + x = 4(3 + x)

Now, let's expand and simplify this equation. Start by applying the distributive property to the term 4(3 + x).

4 * 3 = 12

4 * x = 4x

Inserting that back into the equation gives us 39 + x = 12 + 4x, so let's move all of our x terms to one side. Subtract x from each side.

39 = 12 + 3x

Now, let's get x by itself. Subtract 12 from both sides.

27 = 3x

Finally, divide both sides by three to get x.

x = 9.

It will take 9 years for Kevin to be only 4 times as old as Daniel.