Answer:
https://www.khanacademy.org
Step-by-step explanation:
Khan Academy is free and you can choose by grade level or course. It's a personalized learning experience with videos and practice exercises that includes progress tracking.
I could use the points so if you want to mark this as helpful that would be cool :)
Yes because if you add forty and thirty that equals seventy plus twenty is 90 which is a right angle
