Question

how many terms are there in the am 20,25,30.....100,

Answer 1

Tn=a+(n-1)d. here d=5
last term =100=tn
100=20+(n-1)5
100=20+5n-5
100=5n+15
5n=85
n=17
there are 17 terms
hope it helps

Answer 2

HEY DEAR...
HERE'S YOUR ANSWER⬇
We know that :
a = 20 and d = 25 - 20 = 5.
An = 100 = a+(n-1)d.
= 100 = 20 + 5n -5.
= 100 = 15 +5n.
= 100 - 15 = 5n.
= 85 = 5n.
= n = 85 / 5.
= n = 17.
Therefore, there are 17 terms in total.
Any doubts, please ask me in the comments.
I HOPE YOU FIND IT HELPFUL.
@ LB :)