Answer:
200
Explanation:
Multiply 10 by 20 and you'll get 200.
10 pounds = 1 pound gained
? = 20 pound gained
10 : 1
? : 20
1 x 10 = 10
20 x 10 = 200
Hence, the killer whale will have to eat 200 pounds of seal to gain 20 pounds.
hope this helps and is right; p.s. i really need brainliest :)
