Answer:
The answer to your question is x = 2, y = 8 and z = 10
Step-by-step explanation:
Data
Total length = 20 in
3 pieces, x = first piece
y = second piece
z = third piece
Process
1.- Write equations that help to solve this problem
       4x = y              Equation l
       5x = z              Equation ll
       x + y + z = 20        Equation lll
2.- Substitute equation l and ll in equation lll
      x + 4x + 5x = 20
3.- Solve for x
            10x = 20
              x = 20/10
              x = 2 in
4.- Calculate y and z
        y = 4(2)
        y = 8 in
        z = 5(2)
        z = 10 in