How do we graph anything? Make a table of values for x and y and then plot each point. After plotting each point on the xy-plane, connect each point with a straight line or curve (depending on the function).
In this case, we must first isolate y.
y = (-4/3)x + 8y
y - 8y = (-4/3)x
-7y = (-4/3)x
y = (-4/3)x ÷ (-7)
y = (4/21)x
Now follow the steps above.
Each pack of batteries cost $21 each.
And then you have $63.
The operation to be used: Division.
63 ÷ 21 ==
Answer: 3
= You can buy 3 packs of batteries with your $63.
