Since both of these times are in the P.M., each hour has 60 minutes and 2:30 is half, add 30 minutes to get 3:00 P.M. and then add 3 hours to get 6:00 P.M. . 3 hours and 30 minutes added to 2:30 P.M. equals 6:00 P.M. :)
10 9/10.... because 10 can be divided into 109 10 whole times with a remainder of 9 so you put the 9 over the original denominator which is 10 so 9 over 10