No of minutes in a day=1,440 min
no of baths coldtap can fill=1440/18=80 baths
no of baths hottap can fill=1440/15=96 baths
no of baths the plug hole can fill=1440/10=144 baths
so in 24 hours we have 80+96-144=32 baths
so each bath would take 1440/32=45 minutes
i hope this helps u..