Answer:
200
Explanation:
The LCM of 4 and 5 is 20. Since you know this, you would multiply this LCM by how much you would multiply to get 40 from 4 or 50 from 5.
4 * 10 = 40
5 * 10 = 50
Since you multiply these factors by 10, you would also multiply the LCM by 10.
20 (LCM of 4 and 5) * 10 = 200
The LCM of 40 and 50 is 200.