which term of ap13 21 29 ........ will be 48 less than its 19 th term

AP: 13 , 21 , 29,....
Here , a = 13 , d = 21 - 13 = 8 , n = 19
We know that ,
a_n = a + (n - 1)d
a₁₉ = 13 + ( 19 - 1)8
a₁₉ = 13 + (18) * 8 = 13 + 144 = 157
Thus, a₁₉ = 157
But , we have to find the term which is 48 less than the 19^th term.
a_n= a₁₉ - 48
a_n = 157 - 48 = 109
Now , the term which is 48 less than 19th term is -:
a_n = a + (n - 1)d
109 = 13 + (n - 1)8
96 = (n - 1)8
n - 1 = 96/8 = 12
n = 12 + 1 = 13
Hence , its 13th term will be 48 less than its 19th term.