Write a complete C++ program that: 1) Prompts the user to enter from the keyboard one number and store the number in the double variables x 2) Calculates the value of the double f as follows: 14 X 2) Display the value of f. (1) Sample Input/output Enter the number x = 3 The value of f= 19.0 (2) Sample Input/output Enter the first number x = 3.4 The value of f = 21.0 f = +5*x