Type the correct answer in the box. Use numerals instead of words.

Nina glues pictures on a rectangular piece of cardboard.

The piece of cardboard is 20 inches long and 9 inches wide.
Each rectangular picture is 7 inches long and 4 inches wide.
She glues 3 pictures on the cardboard. The pictures do not overlap.

What is the area of the cardboard that is not covered by pictures? square inches