Kim is 5 years older than her brother Jack. If the sum of their ages is 21, find each of their ages.

16

Step-by-step explanation:

x+5=21

-5   -5 (subtract 5 from both sides)

x=16

9514 1404 393

Step-by-step explanation:

Let k represent Kim's age. Then Jack's age is k-5 and the total of their ages is ...

  k + (k -5) = 21

  2k = 26 . . . . . . . add 5, collect terms

  k = 13 . . . . . . . . . divide by 2; Kim's age

  k -5 = 8 . . . . . . . Jack's age

Kim is 13; Jack is 8.

step-by-step explanation:

to find if any function is an inverse of the other, put the first equation in as x in the next one. then simplify and solve. if at the end you get the statement y = x, then it is an inverse. if you get anything else, it is not.