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

Step-by-step explanation:

Expression given → 4 - 9x + 21

Chang's expression → 4 - 3(3x + 7)

Chang's expression is incorrect because the correct expression is [4 - 3(3x - 7)]

Benjamin's expression → 4 + 3(3x + 7)

Benjamin's expression is incorrect because the correct expression is [4 - 3(3x - 7)]

Habib's expression → 4 + 12x

Habib's expression is incorrect because the correct expression is [4 - 3(3x - 7)]

Correct expression → [4 - 3(3x - 7)]

cross multiplying, we get :

⇒ (3) × (5) = (9) × (x)

⇒ 15 = 9x

step-by-step explanation: