Answer :
Answer:
-36
Step-by-step explanation:
21, 18, 15, 12....
All you have to do is subtract 3 less on each number you get, until u get to the twentieth term....
21, 18, 15, 12, 9, 6, 3, 0, -3, -6, -9, -12, -15, -18, -21, -24, -27, -30, -33, -36
-36 is the twentieth term of this arithmetic sequence
Hope this helped!
Have a supercalifragilisticexpialidocious day!