Question

What will be the values of S8-a4 for the following A.P 4,9,14.........,254.

Answer 1

A=4 d=9-4=5
S8=8/2(2(4)+(7)(5))
=4(8+35)
=4*43
=172

Now t4=4+3(5)=4+15=19

According to question,
S8-t4=172-19
=153

Hope it helps you dear.....

Answer 2

S8-A4 = 172-19=153
Answer is 153