Ms. Johnson asked her class to write an
equivalent expression to
14 − 9 + 21 − 7 + 2.
Riley wrote the expression
7(2 − 3 − 1) − 7
Ahmad wrote the expression
7(2 − 3 − ) − 7
Ariana wrote the expression
7(2 − 3 − ) − 7
Who is correct? Explain how you know.