Do all three questions for brainliest.

What are the domain and range of f(x)=[1/5]x

Solve the system of equations. y= 2x y= x^2 - 15

The graph shows the distance y, in inches, a pendulum moves to the right (positive displacement) and to the left (negative displacement), for a given number of seconds x. how many seconds are required for the pendulum to move from its resting position and return? enter your answer in the box.