Katrina used 2 5/6 packs of mechanical pencils in the first 2/3 of the year. At what rate is Kelly using mechanical pencils?
A. 1 8/9 packs per year
B. 2 1/6 packs per year
C. 3 1/2 packs per year
D. 4 1/4 packs per year

Katrina is using 21//6 (B) packs per year

since your problem is x^4 = 81, what you have to undeo is the "to the fourth power" part.

the inverse (opposite operation) of "to the fourth power" is "to the fourth root".

  (x^4) ^ ¼   = 81 ^ ¼  

  81 = 3^4     so (3 ^ 4) ^ ¼   =   3 ^ 1   = 3

by hand: (3 ^ 4) ^ ¼   =   3 ^ (4 x ¼) = 3 ^ 1   = 3   (when you take a power to a power, multiply the exponents.)

or, do it by calculator. one way of finding the fourth root is to use ^ (1/4)

step-by-step explanation: