John's sister is twice his age. In 5 years the sum of their ages will be 31. How old are John and his sister now? Briefly explain how you arrived at your answer.

Like usual, we can solve this question using an equation. Let’s assume that John’s age is x, and his sister’s age is y.

x = 2y

To figure out John’s age, we need to know his sister’s age. He’s 2 times older than his sister.

x + y = 27

The sum of their ages is 27, and we can substitute the value of x here to figure out y.

2y + y = 27

We can now simplify this, and get y by itself.

3y = 27

Now, we can divide by 3 to get the y by itself.

y = 9

We now know that John’s sister is 9.

Now, using our original equation, we can substitute in the value of y.

x = 2(9)

We can simplify this.

x = 18

John’s age is 18!

Hope this helps.

can you rephrase the question ? it is unclear : -)

step-by-step explanation: