Answer:
A) 10x + 8. B) 6x² + 5x -21
Explanation:
A) We have (3x + 7) on the bottom and (3x + 7) on the top.
We also have (2x - 3) on two opposite sides.
Adding them up gives 3x + 3x + 2x + 2x + (7 + 7 - 3 -3) = 10x + 8 (cm).
B) For the area, we only need to multiply (3x + 7) and (2x - 3).
(3x + 7) (2x - 3) = 6x² -3(3x) + 7(2x) - 3(7)
= 6x² - 9x + 14x - 21
= 6x² + 5x - 21