my suggestion...

1. functionality
2. schedule
3. resources

用一张白纸，叠一个“等边三角形”，每一边写上上述1，2，3点。

跟老板解析：
如要10个functionality，就得花10个schedule，10个resources -- “等边三角形”。假如只有6个schedule （i.额。6天），那就得增加resources 或减少functionality！

please provide your feedback and results after meeting with your boss.

ref. to Application Management Lifecycle -- AML, either W. or I. methodology