Macintosh HD

I own a mac book pro 13" ratina display 128gb with os x 10.11.6

in storage section it showing that my mac has 90gb of app on it and 85 gb of free storage

which sum upto 175gb!!(175gb!=121gb) .when i checked i found out that app actual space occupied by

apps are only 14.9gb is thr a virus on my mac ?...if yes thn hw ...mac usually are virus protetected ...right?