I don't understand. Could you perhaps be a little bit more clear?
I solved with addition elimination, and matrices elimination and received the same answer. (0,0,-3) I hope that helps.
Answer:
y = 60
Step-by-step explanation:
From the information we get:
x quantity of 4 dollars coffee used in the mix
y quantity of 7 dollars coffee used in the mix
For the quantity of coffee to be sold a 7 $/pound ( 90 pounds)
Then 6*90 = 540 $
Therefore
x + y = 90 and
4*x + 7*y = 540
A two equations system we solve for x and y
y = 90 - x
4*x + 7* ( 90 - x ) = 540
4*x + 630 - 7*x = 540
- 3*x = - 90
x = 30 pounds and
y = 90 - 30
y = 60
We should use 60 pounds of the seven $ coffee
Posting screenshot of my answer in the linked question in case it gets deleted.
p-20