设桃树的棵树为x棵,柳树的棵树比桃树少百分之四十,所以柳树的棵树(1-40%)x,依题意得:
x+(1-40%)x=120
x+60%x=120
1.6x =120
x =75
(1-40%)x =45
答:桃树的棵树为75棵,柳树的棵树为45棵.