Ministers have chosen to make "savings" predominantly off the back of low-income pupils in an education system that was already stacked against them. 

参考译文：部长们选择主要靠低收入学生来“节约”，而这一教育体系本已对他们不利。

重点单词和短语解析

(1)choose to do sth 选择做某事

(2)savings 节省;节约

(3)predominantly adv.  占主导地位地; 显著地; 占优势地;

(4)off 从…（获得）

(5)the back of low-income 低收入支撑/支持

(6)in an education system在教育体系

(7)stack against 对…不利