You need to find the width of the stream. you cannot measure the width directly, so you draw a diagram showing lengths that you can measure. your diagram contains two similar triangles, one in the stream and one on land. use the diagram to find the width of the stream.

There is no diagram, therefore we can't answer the question.

Best answer that i found on yahoo ok   set :   x= length of 2nd piece in cm  x- 3= length of 1st piece in cm  x-4= length of 3rd piece in cm  then since you know they all came from the 20 cm ribbon you add them together and set them equal to 20x+ x-3 +x-4 = 20  3x - 7= 20  3x= 27  x= 9  the shortest piece is the third piece which is x- 4  x-4  9-4 = 5  the length of the smallest piece is 5 cm.  the other lengths are  9 cm  6 cm