You have a large container of castor oil. You have used 34 quarts of oil. Fifteen percent of the castor oil remains. How many quarts of castor oil
remain?
co

Explanation:

x = original amount of caster oil (in quarts)

Since 15% remains, this means you used 85% of the original amount x.

Note how 15% + 85% = 100%

So,

85% of x = 34 quarts

0.85x = 34

x = 34/0.85

x = 40

You started with 40 quarts of oil.

15% of that remains, meaning 0.15*40 = 6 quarts of oil are left over.

We could also solve like this

(amount used)/(amount total) = (percent)/(100)

34/x = 85/100

34*100 = x*85

3400 = 85x

85x = 3400

x = 3400/85

x = 40

So we end up with the same x value as before, and we follow the same set of steps at the end of the first section to end up with the answer of 6 quarts.

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: