A grid of two rows and four columns has one extra slanting line from the top-left to the bottom-right corner of the second square in the top row. How many quadrilaterals are there?

The grid alone has $\left(\genfrac{}{}{0ex}{}{5}{2}\right)\times \left(\genfrac{}{}{0ex}{}{3}{2}\right)=30$ rectangles. The slanting line adds 4 four-sided figures using it as a side: in the top row, one reaching the left edge and two reaching the upright lines on the right; and one going down through both rows. Total $30+4=34$.