Correct spelling, explanation: the number fifteen is one of the oldest English words. It already appeared in Old English as the form fiftyne. Hence, the only correct form is fifteen, not fiveteen.

Definition of fifteen:
the cardinal number between fourteen and sixteen,
More than fifteen people were injured in a two-car accident that occurred in Warsaw three days ago.
When I was fifteen I like walking with my dog in the forest.

Incorrect spelling, explanation: fiveteen is the mistaken word, consisting of two components five and teen. English learners think that this is appropriate because they remember the number five. Logically speaking, the form fiveteen would be correct but it is not due to the origin of this word.

Incorrect spelling

Incorrect spelling

Incorrect spelling

Incorrect spelling

Incorrect spelling

Incorrect spelling

Incorrect spelling