Answer
$5(x+4)+3x=$
$=(5x+20)+3x\quad $(distributive property)
$=(20+5x)+3x\quad $(addition: commutative property)
$=20+(5x+3x) \quad $(addition: associative property)
$=20+(5+3)x\quad $(distributive property)
$=20+8x\quad $(combining like terms, simplification of parentheses)
$=8x+20\quad $(addition: commutative property)
Work Step by Step
Commutative properties: $a+b=b+a,\qquad ab=ba$
Associative properties:$ a+(b+c)=(a+b)+c,\qquad a(bc)=(ab)c$
Distributive property: $\quad A(x+y)=Ax+Ay$
Combine like terms by combining the coefficients of the terms and keeping the same variable factor.
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$5(x+4)+3x=$
$=(5x+20)+3x\quad $(distributive property)
$=(20+5x)+3x\quad $(addition: commutative property)
$=20+(5x+3x) \quad $(addition: associative property)
$=20+(5+3)x\quad $(distributive property)
$=20+8x\quad $(combining like terms, simplification of parentheses)
$=8x+20\quad $(addition: commutative property)
