Question

plz ans the 3rd ques

Answer 1

Last term = a + (n -1)d
a = first term
n = number of terms
d = difference
taking -77 as last term

-77 = -2 + (n -1)(-5)
-75 = (n-1)(-5)
15=n-1
n = 16
number of terms = 16

sum of AP is
$\frac{n}{2} (a + last \: term)$
8(-2 -77)
8 (-79)
Sum = - 632