Explain why you can remove an x tile from each side of the mat

What are “like terms”? why can we only add like terms?

Can you me with this question? i'll reward *30 points i just need with this one question so that i could solve the others. * edit: i originally set up the question to reward 30 points, but for some reason i can only reward 15. if you don't get 30, then i'm sorry. i'm still kind of new to this site

Alarger number is double the sum of a smaller number. the larger number is 2 less than 3 times the smaller number. if y represents the larger number and x represents the smaller number, which equations model the situation