Pls help. The answer needs to have 3x^2 in front I’m sure with another answer as well. I asked a different question like this but got it wrong because they only gave me half of the answer.

Answer:
9x^2+21x
Step-by-step explanation:
Area formula for a rectangle: L · W
L=3x
W=3x+7
Since it says multiplying polynomials
I'm guessing you do the Box method
3x(3x+7) = 9x^2+21x
Hope this helps! :)
Correct me if I'm wrong