Science Biology question about mass of animals? 10 points best answer!

A blue whale eats 4000 kg per day and a rat eats about 15 g per day. Both animals replace about 5 percent of their body mass each day.
What is the approximate mass of both animals?
I can't figure this question out, please help and 10 points! Thank You!!

It seems to be stating that the mass of food they are eating is 5 percent of their total body weight. In that case you have to figure out, say in the blue whale's case, 5% of what is 4000?

Approximate mass of Blue Whale:
(.05)(x) = 4000 kg
x = 80,000 kg mass for a Blue Whale

Approximate mass of Rat:
(.05)(x) = 15 g
x = 300 g mass for a Rat

*Note the difference in units! Kg vs g.

Hope this helps!