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. 4-9+21 4-3(3x+7)
changs expression is ___ because

4+3(3x+7) benjamin's expression is ___ because

4+12x
habib's expression is ___ because