I've done a lot and got to 99%. i've already practiced everything and it won't give me a mastery challenge. it wants me to practice something, but i have nothing to practice.

I don't know what website this is, but one of these solutions may help:

Step-by-step explanation:

If this is controlled by your school, contact your teacher and tell her what is going on, as she might be able to help you. Take a picture of this page you have posted, as to save and remember what you have accomplished if anything goes wrong with your computer. Your teacher should be able to help you with this problem, and she should give you credit for your work if your work does not save.

If this is controlled by you, as in you created your own account, contact the website itself, and see if they can help you. Keep asking and asking until someone helps you. [In all honesty, people will have to help you if you are annoying them by pestering them to help you. They will want to finish the job and get rid of you because you are annoying, but hey! At least it works!]

If these don't work then I don't know how to help you.

I do hope this helps though!

it’s supposed to be -4+45=41

step-by-step explanation: