Three students were given the expression shown and were asked to take a common factor out of two of the terms.
Use the drop-down menus to complete the statements about whether each student's
answer is an equivalent expression. Then choose an expression that is equivalent.

Chang is incorrect because his factoring results in -21 instead of positive 21.

Benjamin is incorrect because his factoring results in positive 9x instead of -9x.

Habib's answer is incorrect because 4 + 12x is not equivalent to the expression above.

A correct factor would be: 4-3(3x-7)