Why is the value of -9 is not-3

Which statement is true? the given sides and angles cannot be used to show similarity by either the sss or sas similarity theorems. the given sides and angles can be used to show similarity by the sss similarity theorem only. the given sides and angles can be used to show similarity by the sas similarity theorem only. the given sides and angles can be used to show similarity by both the sss and sas similarity theorems.

F(n + 1) = f(n) – 8. if f(1) = 100, what is f(6)?

If x is 6, then 7x= a. 13 b. 42 c. 42x d. 76