Question 71646
1. 
Let x=Tim's weight
Then (x+10)=Kevin's weight
And x+(x+10)=470 get rid of parens
x+x+10=470 collect like terms
2x+10=470

2.
Let x= cost of his old one
Then  (x-$178.50)= cost of his new one
And x+(x-$178.50)=$3500 get rid of parens
x+x-$178.50=$3500
2x-$178.50=$3500 

3.
Let x=Kelsey's age
(x-5)=Kelsey's age five years ago
Then (x-4)=Kierra's age
((x-4)-5)=Kierra's age five years ago
And (x-5)+((x-4)-5)=14  get rid of parens
x-5+x-4-5=14  collect like terms
2x-14=14


4.
Let x=length
Then x/3=width
Perimeter=2l+2w
And 2x+2(x/3)=56  get rid of parens
2x+2x/3=56  Multiply each term by 3
6x+2x=168


Hope this helps---ptaylor