[Grammar] come up with & make up

[Betty zhang]

Question:
We must come up with a plan to improve your math.
OR
We must make up a plan to improve your math.
Why?
Thanks.

 

[emsr2d2]

Question:
We must come up with a plan to improve your math.
OR
We must make up a plan to improve your math.
Why?
Thanks.

Which one do you think is correct and why? What do you understand by "to come up with" and "to make up"?

 

[Boris Tatarenko]

Hello.
Can we replace "understand by" with "understand under"?

Which one do you think is correct and why? What do you understand by "to come up with" and "to make up"?

Thanks.

 

[Rover_KE]

Can we replace "understand by" with "understand under"?

No.

 

[Rover_KE]

Can we all wait until the OP has responded to post #2 before offering alternative suggestions?