Question

Minimize w= y1+y2+4y3
subject to y1+2y2+3y3>=115
2y1+y2+y3<=200
y1+ y3>=50
with y1 >=0 y2>=0 y3>=0

Answer 1

Graphics is too hard for me to use with three variables. Here is a good outline how to use Excel (and compariable) spreadsheets.

http://www.cob.sjsu.edu/anaya_j/LinPro.htm

Answer 2

THe sign change in row three is not a sign change it is a misprint it really is and >= sign.