Answer:
I guess u want to know the quadratic function and its formula is, AX*2 + BX + C. Otherwhise you want to know how to get 0 and get the Xm if you want to know how to solve a quadratic. That formula is, (-B +/-
(B*2 - 4AC) ) . 1/2 (where A, B and C are the number at the original function).
Step-by-step explanation:
Let p be the prize of a pen and m the prize of a mechanical pencils. If you buy six pens and one mechanical pencil, you spend 6p+m. We know that this equals 9, because you get 1$ change from a 10$ bill.
Similarly, if you buy four pens and two mechanical pencils, you spend 4p+2m, which is 8$, because now you get a $2 change. Put these equation together in a system:

Now, if you multiply the first equation by 2, the system becomes

Subtract the second equation from the first:

Plug this value into the first equation to get

Answer:
2.88
Explanation:
If you break down the equation we see that 8 is the number of boxes and 1.44 is the price of each box. So if you wanted to change the equation the formula would be: (1.44)x = cost so if you wanted to figure out how much 2 boxes would be, you just plug in 2 for x and you get (1.44)2 = 2.88