He should have subtracted the discount and added the sales tax
<span>you could have 3.15=100 times 0.0315, 10 times 0.315.</span>
Well on this problem recall area of a rectangle is defined by:
A = lw our w = 1/6 and our l = (x +

) we have let 'x' represent our original length.


12x + 8 = 11
12x = 11 - 8
12x = 3
x =

So our original length is