Answer:
The total number of chromosome in a skin cell is equal to 78
Step-by-step explanation:
The sperm is usually haploid i.e it will contains only half of the total chromosome number.
Therefore , if the total number of chromosomes is "n" , then the number of chromosome in the sex cell will be "n/2"
Thus, 39 chromosome is just the half of total chromosome number.
Now a skin cell is a diploid cell and it will contain all the chromosome i.e "n"
As we know

Hence, the total number of chromosome in a skin cell is equal to 78