5.30 It's half past five.
11.45 It's eleven forty-five. It's a quarter to twelve. It's forty-five (minutes) past eleven.
3.05 It's five minutes past three. It's fifty five to four.
7,50 It's ten minutes to eight. It's fifty minutes past seven.
6.15 It's six fifteen. It's a quarter past three. (It's forty-five minutes to seven.)