He said, on her income, with some changes, she would be able to buy an investment unit within two years, which she did.
on her income, with some changes 这两个介词短语，与 said 无关，而是修饰后面的句子。
on：根据；依据。on her income 根据她的收入情况
with：如果，只要；在......情况下。with some changes 只要作一些调整或改变
