Tree diagram question

To convert celsius temperatures to fahrenheit, you can use the expression (c + 32). tom says that another way to write this expression is c + 32. what error did tom make?

The lengths of two sides of a triangle are 9 and 15. what can be said about the length of the third side? a. it must be greater than or equal to 6 and less than 24. b. it must be greater than or equal to 6 and at most 24. c. it must be greater than 6 and less than 24. d. it must be greater than 6 and at most 24.

If a + b = 28 and a - b = 10, then b =?