Evaluate: 21m-3mp+4p-28

Expression: $21m-3mp+4p-28$

Factor out $3m$ from the expression

$3m \times \left( 7-p \right)+4p-28$

Factor out $-4$ from the expression

$3m \times \left( 7-p \right)-4\left( -p+7 \right)$

Factor out $7-p$ from the expression

$\left( 7-p \right) \times \left( 3m-4 \right)$