Mr. R.’s World of Math

Thief went flying,
A speeding airplane,

Right out my front door,
End of math game…
My homework was safe,
Only one 3 was gone,
The thief had been foiled,
And the legend lives on…
But then I heard Thief,
From somewhere far off,
He screamed out 5,
Then he coughed out a cough…
I smiled a smile,
Although thief wasn’t seen,
I answered his question,
3 X 5 is ____