Three students were given the expression shown and were asked to take a common factor out of two of the terms. 4-9x+21

Chang: 4-3(3x+7)
Chang’s expression is ___ because _.

Benjamin: 4+3(3x+7)
Benjamin’s expression is ___ because _.

Habib: 4+12x
Habib’s expression is ___ because _.

Equivalent Expression
The correct simplification of this expression _.

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