Answer:
240
Step-by-step explanation:
This is the answer because:
1) 240 is a number between 150 and 310
2) 240 is a multiple of 20
3) 3 is one of the factors of 240
4) The sum of 240 is 6:
2 + 4 + 0 = 6
Therefore, the answer is 240.
Hope this helps! :D