we are given
airthematic sequence
we can use nth term formula

n is number of terms
an is nth term
d is common difference
a1 is first term
We are given
a7=40
we can use it



a18 = 106


we can subtract both equations



now, we can find a1

we can plug d=6


12th term:

now, we can plug values



so, 12th term is 70...........Answer
The answer is 480 because 144/3 is 48. You multiply 48 and 10 to get 480
The distance around a figure is called the perimeter.
Hope this helps :)