Answer:
[see below]
Step-by-step explanation:
[tex]\frac{8}{m}-\frac{b}{n}\\\\\rightarrow \text{Adjust based on LCM}\\\text{LCM: } mn\\\\\frac{8n}{mn}-\frac{bm}{mn}\\\\\boxed{\frac{8n-mb}{mn}}[/tex]
Hope this helps.
