The answer is 16/34 OR 8/17. 8 over 17 is a fraction, so i wrote it as such. If triangle x was doubled, then both 8 and 17 would be multiplied by 2.
This results in the fraction 16/34.
This is your answer. However, 16/34 also reduces to 8/17 by simplifying. This is because the triangle x has the same ratios as triangle 2x
I hope this helps you!!! :))