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.

4-9x+21

Chang: 4−3(3x+7)
Chang's expression is (incorrect/correct) because (he factored correctly/he did not divide 21 by -3 correctly/he did not divide -9x by 3 correctly/he cannot simplify 4-9x/he cannot add -9x and 21/he should have factored out 4 instead).

Benjamin: 4+3(3x+7)
Benjamin's expression is (incorrect/correct) because (he factored correctly/he did not divide 21 by -3 correctly/he did not divide -9x by 3 correctly/he cannot simplify 4-9x/he cannot add -9x and 21/he should have factored out 4 instead).

Habib: 4+12x
Habib's expression is (incorrect/correct) because (he factored correctly/he did not divide 21 by -3 correctly/he did not divide -9x by 3 correctly/he cannot simplify 4-9x/he cannot add -9x and 21/he should have factored out 4 instead).

The correct simplification of this expression is (4+11x/5x+21/4-3(3x-7)/4+3(3x-7)/4- 3(3x+7)/4+3(3x+7))