Answer:
3
Explanation:
In this triangle ABC, the leg lengths are AC and BC, being x and x+7, respectively. So, the area can be listed as: 15 = (1/2) * x * (x+7). Simplifying that gets x^2 + 7x = 30 -> x^2 + 7x - 30 = (x-10)(x-3). So, x = 3 since it cannot be negative.