Answer:
The average weight of new born otter was,

Explanation:
Let average weight of new born otter be x.
As per the given statement: At birth it's weight was 7/8 kilograms which is 9/10 kilogram less than the average weight of a new born otter in the aquarium
"
kg less than average weight of a new born otter" means

As per the given information, we have;

Add
both sides, we have;

Take LCM of 8 and 10 is, 40
⇒

Simplify:

Therefore, the average weight of new born otter was,
