Please help need anser

Determine whether the set of whole numbers is closed under addition. explain why the set is or is not closed. give an example.

Shane can shovel the driveway in 4 hours, but if his sister it would take 2 hours. how long would it take taylor to shovel the driveway alone

Wich statement could be used to explain why the function h(x)= x^3 has an inverse relation that is also a function