$5x \times 2x-5x \times 3-2x-1 \times \left( -3 \right)$
Calculate the product$10{x}^{2}-5x \times 3-2x-1 \times \left( -3 \right)$
Calculate the product$10{x}^{2}-15x-2x-1 \times \left( -3 \right)$
Any expression multiplied by $-1$ equals its opposite$10{x}^{2}-15x-2x+3$
Collect like terms$10{x}^{2}-17x+3$