had exactly the same question and I found three possible solutions on the internet.
Use an USB Y-cable and an active USB-Hub; problem is u need two sockets, cause u have to charge tablet and usb hub separate
I found this adapter from Dell: Dell 470-ABES CUS The manufacturer says it only works with Dell tablets, but I found some reviews that it works with every tablet, that supports OTG. So u can try, if this adapter works for the X98, but I can’t guarantee that.