Answer:
= 403
Step-by-step explanation:
the sum to n terms of an arithmetic series is
=
(a + l) ← a is the first term and l the last term
here a = - 5 and l = 67 , then
=
(- 5 + 67) = 6.5 × 62 = 403
15 + 8= 23
23/2 = 11.2
-5 + 8 = 3
3/2= 1.5
Answer is (11.2,1.5)
60° because its not hafe evin and 90° is hafe so its 60°