the word similar means the same shape but different sizes. That means that you can think of this problem as ratios. The ratio for the first triangle would be 14:14:18. Since the second ones ratio is 7:7:x we know that the seven was found by dividing 14 by two so we do that with the rest of the of the number to find x you divide 18 by two and get 9. So x=9.
