weight of three tables

Question

the total of three tables is 16.9 pounds. The first table is twice as heavy as the second table.  The third table is 1/3 the weight of the second table.  what is the weight of the first table? 

 

I would love to know how to show my son how to solve

Answer 1

Let x be the weight of the first table, x/2 is the second, the third x/6

 

x+.5x + .167x = 16.9

 

1.667x = 16.9

 

10.14 pounds is the weight of the first, 5.07 pounds is the weight of the second, 1.69 pounds is the weight of the third

 

 

 

OR

 

Let y be the weight of the second table, and 2y be the first, and y/3 the third

 

y +2y+y/3 = 16.9    Multiply all terms by 3 to eliminate the fraction

3y +6y+y = 50.7

10y = 50.7

y= 5.07 pounds  second table, 10.14 pounds first table, 1.69 pounds is the weight of the third table