How to sum two binary numbers
Your number has a fixed binary point. This means the low byte is to be divided by 256 to get the right fraction What it actually means is:

30 + 192 / 256 = 30 + 0.75 = 30.75

This is a great format because you can simply use the CPU's integer math with it, which is simple and fast. Only when needed to print, you have to convert it in a way the (binary) point is respected. Only for multiplications and divisions you need to shift the result for correct magnitude. Think about it, this is exactly the same as you learned in primary school with the decimal numbers.

With the high byte, the rightmost bit, bit0 has a weight of 20=1. The bit to the left has weight 21=2 and the bit next to that 22=4 ... etc.

The bits to the right, the low byte have weigths 2-1=0.5 and the bit to the right of that 2-2=0.25 ... etc. up to 2-8=1/256.