Find the vertices and foci of the hyperbola with equation x^2/9 - y^2/16 = 1

Abike shop sells you a bicycle for $63 and a helmet for $21. the total cost is 150% of what the shop spent originally. how much did the shop spend originally? how much profit did the bike shop earn by selling the bicycle and helmet to you ?

If f(x) = x+8 and g(x) = 4x- 3, find (f+g)(x)

F(x) = 1/x g(x)=x-4 can you evaluate (g*f)(0) ? why or why not?