40. Shrek and Iron Man start from the same place to go to Universal Studios. Shrek walks slower and leaves 5 minutes earlier than Iron Man. Iron Man can catch up with Shrek 15 minutes after he starts. If Shrek walks 5 meters more per minute and Iron Man walks 10 meters more per minute, under the same conditions, Iron Man can catch up with Shrek 13 minutes after he starts. Then, Shrek's initial speed is $\qquad$ meters per minute.
$60$