Please explain how to solve all the parts in details

It is a common misconception held by many Econ 1 students that a linear demand has a constant elasticity of substitution. Suppose we have the following demand function: gx (px) = a bpx, where a and b are some positive constants. (a) Solve the demand function for px. Plot the demand function, placing px on the vertical axis and gx on the horizontal axis. (b) Compute the price elasticity of demand: ex'px (c) As you move down along the demand curve (as px decreases and gx increases), does the demand become more or less elastic