NEEED HELP ASAP PLZZZ What is the sum of the measures of the interior angles of an 18-sided figure?

Ineed me i stuck and i don’t want to get it wrong

With this question substitute t=3 and t=5 to determine if the two expressions are equivalent. 4(t + 3) 4t+12 which statements are true? check all that apply. a. the value of both expressions when t =5 is 32. b. the two expressions are not equivalent. c. the value of both expressions when t=3 is 15. d. the value of both expressions when t=5 is 23. e. the two expressions are equivalent. f. the value of both expressions when t=3 is 24.

Do you mind if you guys me with this question i’m on number 8