We need to set this up as an algebra problem.
But before we do that, we need to make sure all our numbers are in the same base, so well convert all the numbers to yards, becuase that's what they sell the concrete in.
12 feet = 4 yards
6 inches = 1/6 yards
And we know that width*length*height @ $98 per yard = 108.89
So width*length*height*98=108.89
We don't know the width, so let's call this "x"
x*4*1/6*98=108.89
x*4/6*98=108.89
x*392/6=108.89
x*65.3333=108.89 ---Divide both sides by 65.3333
x = 1.66666
x = 1 and 2/3 yards ---Change to feet by multiplying the right side by 3
x = 5 feet
So the width of the driveway is 5 feet.