The 9th term of an A.p is 32 while the12th termis70.find the sum of it 20th term
"The 9th term of an A.p is 32" ---> a + 8d = 32
"the12th termis70" ----> a + 11d = 70
subract them: 3d = 38
d = 38/3
then in first : a + 304/3 = 32
a = -208/3
term(20) = a + 19d = -208/3 + 19(38/3) = 514/3
You said " find the sum of it 20th term"
That makes no sense.
Do you want the 20th term, which I found for you
or
Do you want the sum of the first 20 terms.
I will let you do the arithmetic for you ...
sum(20) = 10[ 2(-208/3) + 19(38/3) ]
= ....