SOLUTION: The Munson jumbo chocolate bar is rectangular and measures 12 centimeters in length, 10 centimeters in width and 2 centimeters in thickness. Due to escalating costs, management has

Algebra ->  Expressions-with-variables -> SOLUTION: The Munson jumbo chocolate bar is rectangular and measures 12 centimeters in length, 10 centimeters in width and 2 centimeters in thickness. Due to escalating costs, management has      Log On


   

Question 1089485: The Munson jumbo chocolate bar is rectangular and measures 12 centimeters in length, 10 centimeters in width and 2 centimeters in thickness. Due to escalating costs, management has decided to reduce the volume of the bar by 10%. They do not want to alter thickness as this would be easily noted and might alter the bar's popularity. Management decides the new bar will have the same 2 cm thickness but the length and width of the rectangular bar should be reduced by an equal amount (x). What should the dimensions of this new candy bar be?
Heres what i tried:
Volume: 12x10x2=240 cu/cm total volume of original bar
reduced by 10%=216cu/cm
(12-x)(10-x)x2=216
120-12x-10x+x^2=216
2(x^2-22x+120) x 2 = 216
2x^2-44x+120=216
2x^2-44x-96=0
i then solve using the quadratic formula however the numbers i get are too big and dont make sense for this problem...what am i doing wrong??
Thanks for your help!
Answer by ikleyn(52879) About Me  (Show Source):
You can put this solution on YOUR website!
.
(12-x)(10-x)x2=216     It is your first line. Write it in this way: (12-x)*(10-x)*x = 216.
                       Do not use "x" as the multiplication symbol.
                       Next step is to divide both sides by 2 to get (12-x)*(10-x) = 108.
                       It is equivalent to 120 - 22x + x^2 = 108.

                       Now you see that your second line (and all that follows) is WRONG.