Answer: There are 6 pieces of cloth are rectangles and 9 pieces of cloth are triangles.
Step-by-step explanation:
Since we have given that
For every 5 pieces of cloth, 2 are rectangles
So, remaining piece will be of triangle so,

3 are triangles.
Ratio of rectangles to triangles is 2:3.
Now, she needs 15 pieces of cloth to complete her scarf,
So, Number of rectangles is needed is given by

Number of triangles is needed is given by

Hence, there are 6 pieces of cloth are rectangles and 9 pieces of cloth are triangles.