with the marked diagonal line placed as shown. sew on the diagonal line. repeat with the three remaining 2-1/2" x 4-1/2" rectangles of fabric b and three 2-1/2" squares of background fabric.
19) trim 1/4" away from the sewn line and press the seam allowance toward the background fabric.
20) take one of the units completed in step 19 and one of the remaining 2-1/2" squares of background fabric and place them right sides together with the marked diagonal line placed as shown. sew on the diagonal line. repeat with the three remaining step 19 units and the final three 2-1/2" squares of background fabric.
21) trim 1/4" away from the sewn line 