Question

Which term of the A.P. 3 ,8, 13,.... is 78?

Answer 1

first term is 3
common difference is 5 (8-3)
an = 78
using the formula
an= a + (n-1 )d
78= 3 + (n-1) 5
75 = ( n-1) 5
15 = ( n- 1)
16 = n

hope this helps you

Answer 2

hope it helps .......plzz comment