For each of the following $A.P.s$,find the $n^{th}$ term: $10.5, 11.7, 12.9, 14.1, \dots$

How many three-digit numbers are divisible by $7$?

The $\ldots \ldots \ldots \ldots^{th}$ term of the $A.P.$ $200, 196, 192, \ldots$ is $0$.

Determine the $AP$ whose third term is $16$ and the $7^{th}$ term exceeds the $5^{th}$ term by $12$.

Find the number of terms in the finite $A.P.$ $6, 5.5, 5, \ldots, -12$.

To clear a debt,Ajaybhai has to pay $Rs. 100$ in the first monthly instalment,$Rs. 150$ in the second monthly instalment,and onwards he has to pay in each monthly instalment $Rs. 50$ more than what was paid in the previous instalment. He has to pay $24$ monthly instalments in all. What amount will he pay in the $24^{th}$ instalment?