The coefficient of 10x and the last term 16 is what we'll focus on. Specifically just the numbers only (ignore the variable x for now).
Think of two numbers that both multiply to 16, and also add to 10. Those two numbers are 8 and 2 (in any order). You basically find this through trial and error.
8 + 2 = 10
8 * 2 = 16
So it factors to (x+8)(x+2). Since order of multiplication does not matter, this is the same as (x+2)(x+8)