【Analysis】 85 or 75  
20 minutes later, the distance between the two people decreased by $3000-2900=100$ meters;  
Therefore, the speed difference per minute is $100 \div 20=5$ meters;  
Thus, Liangliang's speed is $80+5=85$ meters per minute or $80-5=75$ meters per minute.
14. The distance between location A and location B is 3 kilometers. Mingming and Liangliang start from the two locations at the same time and walk in the same direction. After 20 minutes, they have not met and are still 2900 meters apart. It is known that Mingming walks 80 meters per minute, and Liangliang walks $\qquad$ meters per minute.