Answer:
-30
Step-by-step explanation:
Tn = a1 + (n-1)d = 34 + (-2)(n-1) = 34-2n+2 = 36-2n
hence,
10= 36-2n
2n = 36
n = 13
20 terms from the last term would be 13+20 = 33
T33 = 36-2(33) = -30
63
Total groups: 21
number of students in each group: 3
total = 21 *3 =63
-45
9*(-5)=-45
