What is the solution to the following inequality

This is a table of values that follows a given rule or function. each output comes from the input being applied to the rule.

The moats separating people from the animals are 5 m wide for lions and 4 m wide for the elephants. if the lion’s moat is 4 m deep, how deep should the elephants’ moat be?

Which expression is equivalent to 64 - 9x^2?