Using the graph of f(x) and g(x), where g(x) = f(k⋅x), determine the value of k. Graph of two lines. f of x passes through 1, 2 and 2, 5, and g of x passes through one half, 2 and 1, 5.

I know the answer is -2, but could anybody explain HOW to get the answer?

‼️‼️‼️‼️‼️the pressure exerted on the walls of a container by a gas enclosed within it is directly proportional to the temperature of the gas. if the pressure is 6 pounds per square inch when the temperature is 440 f, find the pressure exerted when the temperature of the gas is 380°f. (show work)