The equation for amount of work done is w=rth, where w represents the work done, r the rate, t the time, and h the number of people or things doing work.
So with the first sentence we have 5=r(20)(5), which simplifies to 5=100r, so r=1/20. Now we substitute this into the equation for our second sentence.
Notice that when we divide e into halves and rearrange those halves, the shape is the same as the shaded area. The shaded area is 1/8 of the total square(try dividing the diagram into only the gray area shape). We know the area of the square is 16, and that e is equivalent to 1/8 the area so its area is 1/8 * 16= 2 square inches.