Piperson, i believe they are completely safe! Stating your first name online with no other information (Living quarters, Town, Parents/gaurdians Names, Etc.) is almost gauranteed not to affect a users experience online. Also, this is a math help forum. I believe it would be more logical to help rather then chase users away. Although i agree khan Academy is a very useful site. I use it myself along with codecademy!
Lily, im not all too familiar with the simplex method, but i believe this may be a trial and error situation. Using familiar experiences, i would guess that although there are two -9's, the lowest negative indicator would still be -9.
If im wrong i do apologize, im only using past experiences to take a logical guess. 
+1002 
