1.In three years, I will have paid off the difference with this, and I don't have to be the person who's always on call to milk.
pay off 付清;取得成功;贿赂;报复
He paid off the debt of his friend with the money raised by his writings.
他用稿费的收入偿清了朋友的债务 。
It has been rather costly to install the machinery, but it should pay off in the long run.
安装这套机械代价很高,但从长远来看它会赚钱的 。