Question

find the sum of following Ap 7+101/4+14........+84​

Answer 1

7+10 1/2 +14+....84

here a=7

d=10 1/2-7=21/2-7=21-14/2 =7/2

Also last term=l=84

first,we find n

an =a+(n-1)d

hence an =l=84