Can someone please help me thank you

Neither of the students are correct.

Step-by-step explanation:

Sarah:

P = 3x + x +7 + 3x + x +7 this first step is correct

    = 6x + 14 this step is incorrect, Sarah forgot to add the other 2 xs

John:

P = 2(x + 7) + 2(3x)

  =  2x + 7 + 6x this step is incorrect, John forgot to distribute the 2 to the 7

  =  8x + 7 incorrect because of the previous step

The answer should've been 8x + 14.

a) 6(2)+6^2+24

   =12+36+24

   =72 square inches

b) 8 inches by 9 inches