$225$ minutes $=3$ hours $45$ minutes.  He started playing at $7.35\text{p.m.}$ 
Kit played computer games for $225$ minutes. When he stopped gaming and decided to head to sleep, he checked the time and noticed that it was $11.20\text{p.m.}$ What time did he start playing computer games? 

a. $7.35\text{p.m.}$ 
b. $8.35\text{p.m.}$ 
c. $8.55\text{p.m.}$ 
d. $9.45\text{p.m.}$ 