Create an algebraic equation based on the word problem below.
Amy class has nine students on roll. There are some new students that join her class and the number of students increases to 16. How many students joined Amy's class? (Answer each part below)
Part a: How would you solve this problem using mental math?
Part b: Define the variable:
Part c: Set up an equation:
Part d: Solve the equation you created.
Part e: Write your final answer in a complete sentence.