What is the inverse of f(x) = 19/x^3

Offering 30 if a plus b plus c equals 68 and ab plus bc plus ca equals 1121, where a, b, and c are all prime numbers, find the value of abc. the answer is 1978 but i need an explanation on how to get that.

What is negative 3/9 times negative 2/8 ?

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?