ITP - Variables - exercise 2

Write a program called age.rb that asks a user how old they are and then
tells them how old they will be in 10, 20, 30 and 40 years. Below is the
output for someone 20 years old.

How old are you?
In 10 years you will be:
30
In 20 years you will be:
40
In 30 years you will be:
50
In 40 years you will be:
60