5/8 x+ 1/16 x = 3/16 + x

x= - 3/5 I'm trying to verify my answer. these are fractions

well, did you try actually verifying it?

(5/8)(-3/5) + (1/16)(-3/5)
= -15/40 - 3/80
= -33/80

3/16 - 3/5
= 15/80 - 48/80
= -33/80

I guess your answer is correct.