More explanation

**Is your feature request related to a problem? Please describe.**
I'm always frustrated when [Something doesn't explain clearly. For example on lesson 22 and 20 you will not understand the lerp function if you only started programming for the first time. And when you begin to work on the practice section, you will need to write how to calculate the goal yourself. It doesn't explain where is cell argument from, do i need to remember to write the formula?]

sorry for the bad english.

**Describe the solution you'd like**
I hope you can explain this lesson 22 more clearly.

**Describe alternatives you've considered**
and probably for the hints too.

**Additional context**
Oh yeah and btw, the lesson 23 have more explanation than the previous one, that is lesson 22