7a. Write a command to create a data frame (name the data frame as employee) with contain 3 variables and 6 observations: employees name, gender and age and the details of each variable, then print the data frame (please make up the data). 7b. Can you calculate the mean of all the employees' age? 7c. Select First N rows with head function. 7d. Display just the 1st column of this framework in the console. 7e. Adding a new column to the employee frame called salary (please make up the numbers), then print this data frame. 7f. Can you calculate the median of the salary variable? 7g. Display the item of data in row 3 , column 3 of the new framework