Why are the numbers I printed by a random array generator not between a range I want.

Question

the range I want the numbers between is 10 and 20, this code is for the black box challenge.
https://code.sololearn.com/claMsRZMJYlT/?ref=app

Answer 1

zc.nextInt((21-10)+1)+10

Answer 2

Use that instead

Answer 3

thank you very much, have a great day and good luck