An $ 8$-foot by $ 10$-foot floor is tiled with square tiles of size $ 1$ foot by $ 1$ foot. Each tile has a pattern consisting of four white quarter circles of radius $ 1/2$ foot centered at each corner of the tile. The remaining portion of the tile is shaded. How many square feet of the floor are shaded?
[asy]unitsize(2cm);
defaultpen(linewidth(.8pt));

fill(unitsquare,gray);
filldraw(Arc((0,0),.5,0,90)--(0,0)--cycle,white,black);
filldraw(Arc((1,0),.5,90,180)--(1,0)--cycle,white,black);
filldraw(Arc((1,1),.5,180,270)--(1,1)--cycle,white,black);
filldraw(Arc((0,1),.5,270,360)--(0,1)--cycle,white,black);[/asy]$ \textbf{(A)}\ 80\minus{}20\pi \qquad
\textbf{(B)}\ 60\minus{}10\pi \qquad
\textbf{(C)}\ 80\minus{}10\pi \qquad
\textbf{(D)}\ 60\plus{}10\pi \qquad
\textbf{(E)}\ 80\plus{}10\pi$
1. **Calculate the area of one tile:**
   Each tile is a square with side length 1 foot. Therefore, the area of one tile is:
   \[
   \text{Area of one tile} = 1 \times 1 = 1 \text{ square foot}
   \]

2. **Calculate the area of the white quarter circles on one tile:**
   Each tile has four quarter circles, each with a radius of \( \frac{1}{2} \) foot. The area of one quarter circle is:
   \[
   \text{Area of one quarter circle} = \frac{1}{4} \pi \left( \frac{1}{2} \right)^2 = \frac{1}{4} \pi \left( \frac{1}{4} \right) = \frac{\pi}{16} \text{ square feet}
   \]
   Since there are four quarter circles on each tile, the total area of the white regions on one tile is:
   \[
   \text{Total area of white regions on one tile} = 4 \times \frac{\pi}{16} = \frac{4\pi}{16} = \frac{\pi}{4} \text{ square feet}
   \]

3. **Calculate the shaded area on one tile:**
   The shaded area on one tile is the total area of the tile minus the area of the white regions:
   \[
   \text{Shaded area on one tile} = 1 - \frac{\pi}{4} \text{ square feet}
   \]

4. **Calculate the total number of tiles:**
   The floor is 8 feet by 10 feet, so the total number of 1-foot by 1-foot tiles is:
   \[
   \text{Total number of tiles} = 8 \times 10 = 80
   \]

5. **Calculate the total shaded area on the floor:**
   The total shaded area on the floor is the shaded area on one tile multiplied by the total number of tiles:
   \[
   \text{Total shaded area} = 80 \times \left( 1 - \frac{\pi}{4} \right) = 80 - 80 \times \frac{\pi}{4} = 80 - 20\pi \text{ square feet}
   \]

The final answer is \(\boxed{80 - 20\pi}\)