What are the justifications for these problems ?

He amount of carbon-14 present in animal bones t years after the animal's death is given by p(t)equals=upper p 0 e superscript negative 0.00012097 tp0e−0.00012097t. how old is an ivory tusk that has lost 26% of its carbon-14?

Write an equation for the function that includes the points (1,4/5) and (2,2/3)

What numbers are included in the set of integers? what numbers are not included?