When a cpu writes to the cache both the item in the cache

Question

Question: When a CPU writes to the cache, both the item in the cache and the corresponding item in the memory must be updated. If data is not in the cache, it must be fetched from memory and loaded in the cache. If ti is the time taken to reload the cache on a miss, show that the effective average access time of the memory system is given by

t_ave = ht_c + (1 - h)t_m + (1 - h)t₁