Answer:
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.
x+0 is the equation.