SOLUTION: i need to justify each step. 5(n+4)+9=(5n+20)+9n =5n+(20+9n) =5n+(9n+20) =(5n+9n)+20

Algebra ->  Expressions -> SOLUTION: i need to justify each step. 5(n+4)+9=(5n+20)+9n =5n+(20+9n) =5n+(9n+20) =(5n+9n)+20       Log On


   

Question 100946This question is from textbook pre-algebra
: i need to justify each step. 5(n+4)+9=(5n+20)+9n
=5n+(20+9n)
=5n+(9n+20)
=(5n+9n)+20
=(5+9)n+20
=14n+20

 This question is from textbook pre-algebra

Answer by BurningFlame_marc(77) About Me  (Show Source):
You can put this solution on YOUR website!
Hello!
I usually justify these kind of problems by stating the property used to each steps.

=5n+(20+9n) APA (we used the associative property of addition to get this)
=5n+(9n+20) CPA (we used the commutative property of addition to get this)
=(5n+9n)+20 APA (we used the associative property of addition to get this)
=(5+9)n+20 DPMA(we used the distributive property of multiplication to get this)
=14n+20 ADDITION(we just simply add to get this)


*associative property of addition means that if you change the groupings of the numbers,it won't affect the sum.
*commutative property of addition means that if you change the order of the numbers it won't affect the sum.