4) Jessica sold half of her comic books and then bought 8 more. She now has 13. How
many did she begin with?

a) Let her  comic books be x

b) as she sold half it will be

  + 8 = 13  ( as she sold half and then she bought 8 more that means plus and then now she have 13 that means = 13)

c ) to solve to find the books she have we need to

+ 8 = 13

Transpose

 = 13 - 8

= 5

x = 5 × 2

x = 10

the comic books were 10

we can even cross- check to see if the value is right instead of x put 10

+ 8 = 13

5 +8 = 13

13 = 13

Cross-checked

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:

here is the

mark brainliest pl