Biology protein question

The gene hepsin codes for a type II transmembrane serine protease. The total gene
length is about 26,000 bp long. The mRNA transcribed from the gene is only about
1800 bp. The CDS (coding sequence) is from base pair 248 to base pair 1499. What is
the length of the protein?
A. 600 amino acids
B. 417 amino acids
C. 600 base pairs
D. 418 base pairs
E. 1800 amino acids

I dont really care if you tell me the right answer, I would just like to know HOW to solve this type of problem. Thanks :D

if the coding sequence is from 248 to 1499 you would subtract 248 from 1499 and then divide the answer by three as its sets of three that make up a codon for a specific aa. The answer is b :)

Hope that helps!