1. Write a function that can accept two variables and calculate the addition and subtraction of it. And also it must return both addition and subtraction in a single return call 2. Write a function that accept name, and salary and display both, and if the salary is missing in function call it should show it as 9000 3. Write a function that returns area of circle. Hint: circle of area is pi*radius*radius a. define the Pi argument default value as 3.14 and radius should take user input. 4. Write a function that returns area of circle but pi value should come automatically. #Hint import math function and access pi value from there