$5\left( {x}^{2}+2x-15 \right)$
Write $2x$ as a difference$5\left( {x}^{2}+5x-3x-15 \right)$
Factor out $x$ from the expression$5\left( x \times \left( x+5 \right)-3x-15 \right)$
Factor out $-3$ from the expression$5\left( x \times \left( x+5 \right)-3\left( x+5 \right) \right)$
Factor out $x+5$ from the expression$5\left( x+5 \right) \times \left( x-3 \right)$