Which term of the AP, 21, 18, 15,... is -81?

Which term of the AP:- 21, 18, 15, . . . is – 78?

Which term of the AP 24, 21, 18, 15,... Is the first negative term?

Which term of the AP 21, 18, 15,… is zero?

Which term of the AP: 21,18,15, is 0?

Which term of the AP 24,21,18,15... is the first negative term

Which term of the series : 21, 18, 15, is -81 ? Can any term this series be zero ? If yes, find the number of terms.

Which term of the AP 5, 9, 13, 17, … is 81?

………. term of AP 21 , 18, 15, ……. is -81.