لَيْسَ عِنْدي قَلَم is curiously not accepted.
Typically, قلم is translated as "pen" only.
Pencil is قلم رصاص
The word cheap appears as missing in the correct answer but is not in the phrase to be translated!
report it then - definitely (another) mistake is lurking there
The last word (right to left) in Arabic is "cheap" and not in the wrong "correct" answer given by Duolingo.
The last word is رصاص (lead).
Cheap is رخيص
Altogether, Pencil in Arabic is قلم رصاص (lead pen) - apparently at some point in history, pencils were made of lead.