Y = -2x + 5 and 2x + y = -7

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

Laura read 1/8 of a comic book in 2 days. she reads the same number of pages every day. what part of the book does she read in a week

The? half-life of a radioactive substance is 20 years. if you start with some amount of this? substance, what fraction will remain in 120 ? years