Find the area of a region bounded by x=0, y=0, and x+y=1?

This area is the area under the line. Rearrange to get y=1-x and put in values so that you get the points (0,1) and (1,0). This makes a triangle of base 1 and height 1, so area is 1/2 x b x h, so area is 0.5!