Rachel bought $12.53 worth of school supplies. she still needs to buy pens, which are $2.49 per pack. she has a total of $20.00 to spend on school supplies. how many packs of pens can she buy?

3

Step-by-step explanation:

20-12.53=7.47

7.47/2.49=3

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: