@arjun sir, please confirm.
As it is mentioned in the question, "Whenever there is a miss in cache, associated block must be brought from main memory to cache for read and write operation".
In case of read miss, we will spend 10ns in cache to check it is present or not + 800 ns to bring the block to cache + further 10 ns to read the required data.
In case of write hit, 50 ns to write the word in the main memory. ( Assuming simultaneous because it is write through policy).
In case of write miss, 50 ns to write the word in the main memory + 800 ns to get the block into the cache.