Need help on #7 , #8 Asap

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

Someone answer asap for ! the boiling point of water at an elevation of 0 feet is 212 degrees fahrenheit (°f). for every 1,000 feet of increase in elevation, the boiling point of water decreases by about 2°f. which of the following represents this relationship if b is the boiling point of water at an elevation of e thousand feet? a. e = 2b - 212 b. b = 2e - 212 c. e = -2b + 212 d. b = -2e + 212

In a timed typing test lara typed 63 words per minute. estimate the number of words she should be able to type in half in hour show your work