设杨树松树总数为X
X/2+11 + X/3-2 = X
X/2+ X/3+11 -2 = X
5X/6 +9 =X
X-5X/6=9
X/6=9
X=54
杨树=X/2+11=54/2+11=27+11=38
松树=54-38=16