Write in standard form 5.2-0.5x=1.9y​

For the answer to the question above, 
Let x = the length of the first piece 
Then 3x = length of the second piece 
And 5x + 2 = length of the third piece 
Now, add all three of these together and set equal to 47: 
x + 3x + (5x + 2) = 47 
Now combine all the like terms and solve for x. Then use that value to find the length of the third piece.