I need help on this asap

13.7ft (1 decimal place)

Step-by-step explanation:

For this question you will have to use Pythagoras theorem.

The formula for the short side is x²=c²-b² and when you put the numbers from this question into it you get x²=15²-6²

15²=225

6²=36

x²=225-36

x²=189

Then, as you want to find x on its own, you would have to square root 189 which is 13.7 (1 decimal place).

Hope this helps :)