Solve problem using the substitution method?
3x - 24 = 7y
4y = 21 – 5x

The answer to your question is   x = 243/47      y = 749 / 329

Step-by-step explanation:

Data

Equations                  3x - 24 = 7y                Equation l

                                 4y = 21 - 5x                  Equation ll

-Solve equation l for y

                                 y = (3x - 24) / 7            

-Substitute in Equation ll

                                 4 (3x - 24)/7 = 21 - 5x

-Multiply by 7

                                 4(3x - 24) = 7(21 - 5x)

-Simplify

                                  12x - 96 = 147 - 35x

-Solve for x

                                  12x + 35x = 147 + 96

                                           47x = 243

                                               x = 243/47

-Substitute x on equation l

                                      y = (3(243/47) - 24) / 7  

                                      y = [729/47 - 24]/7

                                      y = 749 / 329

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: