Ms. johnson asked her class to write an equivalent expression to
14d - 9 + 21k - 7dk + 2
• riley wrote the expression
7dk(2 - 3 - 1) - 7
• ahmad wrote the expression
7(2d - 3k - dk) - 7
• ariana wrote the expression
7k(2d - 3 - d) - 7
who us correct? explain how you know.

No one got the correct answer. The answer is supposed to be 7(2d+3k-dk-1). All the coefficients are divisible by 7, thus only the integers are changed. However, the variables cannot be a factor because they do not have the same variables that all the coefficients must have.