Pls I need help with this question...what’s the answer

If f(x)= 3x+6 which of the following is the inverse of f(x)

Is the point (0, 8) on the x-axis or y-axis? how do you know?

Awater truck is filling a swimming pool. the equation that represents this relationship is y=19.75x where y is the number of gallons of water in the pool and x is the number of minutes the truck has been filling the pool.