we are given

we can use exponent formula

now, we can use this formula

we can add exponent
and we get




So, option-B.......Answer
Answer:
x=80
Step-by-step explanation:
To find the average, we take the numbers, add them up. Then divide by the number of terms we added.
Let x= the unknown number
The average =90
Average = (138+40+102+x)/4
90 = (138+40+102+x)/4
Multiply by 4 on each side
90*4 =(138+40+102+x)/4 *4
360 = (138+40+102+x)
Combine like terms
360 = 280 +x
Subtract 280 from each side
360-280 = 280+x-280
80 =x
Step-by-step explanation:
soln.9×9×9×9
=81×9×9
=729
=6561