1camera=22⇒30cam=22*30=660 (atat a platit el pe ele)
1usb=50⇒120usb=6000(atat a platit el pe ele)
660+50/100*660==660+330=990 (profit din camere 330 total dupa ce a vandut toate camerele)
7590-660-6000=930 (profit general dupa toata vanzarea)
930-330=600(profit din usb)
p/100*6000=600⇒p=(600*100)/6000=10% (profit din usb)
660+6000=6660 (atat a investit el in total)
p/100*6660=930⇒p=(100*930)/6660=93000/6660=13,96(procant total castigat)