设去年种植油菜x公顷,则今年种植油菜（x-3）公顷,得
2400x*0.4+3750=(2400+300)(x-3)(0.4+0.1）
解得x=20
所以x-3=17
答：································· 设去年种植油菜x公顷,则今年种植油菜（x-3）公顷,得
2400x*0.4+3750=(2400+300)(x-3)(0.4+0.1）
解得x=20
所以x-3=17
答：·································