Hi there!
To figure out the value of x, we can use a proportion. Here's the proportion we'd use: 15/7 + x = 9/x. Next, we'll need to cross-multiply in order to get an equation that we are able to solve: 9(7 + x) = 15x. Then, we'll distribute the terms: 63 + 9x = 15x. Lastly, we'll subtract 9x from each side and divide to find the value of x: 6x = 63 | x = 10.5.
Hope this helps!! :)
If there's anything else that I can help you with, please let me know!