How many 2-cm squares have to be
added to the figure below to get a total area
of 80
cm^{2}?

squares

The figure can be regarded as 10 squares, since we can position the two congruent triangles to make a square.

The area of one square is:

2 × 2 = 4
cm^{2}

So the area of the figure is:

4 × 10 = 40
cm^{2}

So the area to be added is:

80 - 40 = 40
cm^{2}

So the number of squares is: