Answer:
150% increase
Explanation:
18 + 18 = 36
Since it adds another 18, this is a 100% increase but we aren't dont yet
Now we add
36 + 9 = 45
Since 9 is 50% of 18, this is a 50% increase
Now we add the total increase in percentage, this is a 150% increase
Hope this helps
-IronWolfX