Question 742303
Let x = number of years need until he is twice your age


So if you add x years to your 17 years of age, you will be 17+x years old (in x years from now)


He will be 49+x years old (x years from now)


You want him to be twice your age, so this means


(His age x years from now) = 2*(your age x years from now)


49+x = 2(17+x)


and that's your initial equation. I won't solve it for you because you just wanted the equation, but I figured the answer doesn't hurt (so you can check). The solution to the equation above is x = 15. This means that in 15 years, he will be twice your age. So in 15 years you will be 17+15 = 32 and he will be 49+15 = 64.