Marcy played the piano for 45 mins she stopped playing at 4: 15 pm at what time did she start playing the piano

We know that
1 hour> 60 min

step 1
convert hours to minutes
4:15> 4 hour +15 minutes> 4*60+15> 255 minutes

step 2
subtract 45 minutes
255-45> 210 minutes

step 3
convert to hour
1 hour> 60 min
x> 210 min
X=210/60> X=3.5 hour
3.5 hour
that means
3 hour+0.5 hour
and 0.5 hour is> 0.5*60> 30 minutes
therefore
3.5 hour> 3 hour +30 minutes>3:30 pm

the answer is
3:30 pm