Janice walks up 3 flights of stairs 5 times per day, for a total of 3*5 = <<3*5=15>>15 flights of stairs
Janice walks down 3 flights of stairs 3 times per day, for a total of 3*3 = <<3*3=9>>9 flights of stairs
In total, she walks 15+9=<<15+9=24>>24 flights of stairs in a single day
#### 24