这个应用允许学生输入数学方程，并获得易于理解的分步解题过程。没有保存历史题目以供回顾的功能。

Build an app that lets students input math equations to see step-by-step solutions.
Add a feature to save past problems for review.

Q: How should the step-by-step solutions be displayed?
A: understandable

Q: How should students access and review their saved problems?
A: no need to save