For question 4 the Y needs to be by itself. So instead of it being x+2y>/-12 it would be y>/-6+x. You would have to subtract x on both sides and then divide 2 on both sides as well. whatever you do on one side, you have to do it on the other side. Hope this helps. After you redo all the equations, you graph them. If you need anymore help , let me know!
What is the question, are we supposed to find the value of "u"? If so, than u is equal to 6 6/7.
The store's sales equate to $6000