by matthewlabau Wed Aug 23, 2017 5:13 pm
For 21,
Here's my initial (written) diagram:
"In" Column = Blank
"Out" Column =
H/SM
M/PT
W/PS
With M in, we know:
-PT are out.
-H is out.
-Either S or W can be in
So we must have L in to satisfy the at least 3 classes condition.