Answer:
C
Explanation:
the perimeter means to go along all 4 sides and sum up the distance.
so, we have
x + 12 + x + 12 + 2x + 2x
we combine all similar terms (the ones with a variable and the constants without a variable)
x + x + 2x + 2x + 12 + 12 = 6x + 24
why do you think the sum of x + x + 2x + 2x is 4x ?
and 12 + 12 is 28 ?
do you need any further explanation, or is this now clear ?