
David W. answered 02/22/18
Tutor
4.7
(90)
Experienced Prof
Draw a picture!
floor down up
------ ------- -----
20 start
19 1
18 2
17 3
16 4
15 5
14 6 5 (what floor us elevator on now?)
13 7 4
12 8 3
11 9 2
10 10 1
9 11 going up
8
7
6
5
4
3
2
1
Now, calculate: 20 - 11 + 5