You did not upload the steps so you will have to look at the correct steps (that I provided below) to determine in which step Fiona made an error.
(2x – 3)(5x² – 2x + 7)
= 2x(5x² – 2x + 7) – 3(5x² – 2x + 7)
= 10x³ - 4x² + 14x -15x² + 6x - 21
= 10x³ - 19x² + 20x - 21