Calculate the mean of 19.7, 20.1 and 20.2 I know how to do it I want to just double check my answers for the test

Write an expression that has three terms and simplifies to 4x - 7. identify the coefficient(s) and constant(s) in your expression

Using only the digits 5, 6, 7, 8, how many different three digit numbers can be formed if no digit is repeated in a number?

What is 60.9643790503 to 5 decimal