#1 is true. The term they have in common is y with an invisible coefficient in-front of the second y term
#2 has zero like terms. 15 has no variable, and the other terms have different variables.
#3 has two like terms, that’s 9 and 8 which add to equal 17. The answer is 3x + 17 aka D.
#4 has two like terms, the numbers with the variable ‘n’. 4n + 7n = 11n. Your answer is 11n + 12 aka D
