Mr. Smith has six children in his family. The list below tells you about the ages of his children. a. No child is more than 10 years old and none of the children are the same age. b. Alejandra is older than 8 years old, but less than 10. c. Debra is the oldest. d. David is 4 years younger than Debra. e. Dexter is 3 years younger than David. f. If Cristina was 5 years older, she would be as old as Debra. g. Joey is older than Dexter but younger than David. Make a chart showing each child and the child’s age. Explain how you got your answers.

Hello!
I suppose that the age of each child is a natural (whole) number.
Then from (b) we get that Alejandra's age is a natural number greater than 8 but less than 10. There is the only such number, it is 9.
Next, from (c) we know that Debra is older than Alejandra and from (a) that her age is no more than 10. So the only possible option is 10.
Now use (d), David is 4 years younger than Debra. So his age is 10 - 4 = 6.
After this, (e) "Dexter is 3 years younger than David" also helps us: his age is 6 - 3 = 3.
What can we do with (f)? Denote the real Cristina's age as x, then 5 years older she would have the age x+5, and it would be equal to Debra's age 10. So x+5=10, subtract 5 from both sides and obtain x = 10-5 = 5.
And finally, from (g) the age of Joey is greater than 3 but less than 6. The possible values are 4 and 5, but 5 is already "used" by Cristina, so the answer is 4.
The resulting chart is:
Name        AgeAlejandra  9Debra       10David        6Dexter      3Cristina     5Joey          4