Answer:
8
Step-by-step explanation:
The ratio of nurses to docters a month ago was 3:5. Now, it's 4:5. You can tell that there aren't 4 nurses because 3 => 4 is only one nurse. If you duplicate both ratios (multiply both sides by 2), you get 6:10 (for a month ago) and 8:10 (now). This is correct because 6+2=8. Hope it helps!