Question 385310
Well lets start with the variable, and let x= the first piece. Now the second piece will now be 4x, and the third will be 3x.

Now let's plug this all into an equation
40=x+4x+3x

Now combine like terms
40=8x

Divide both sides by 8 and you have
5=x

Now substitute in
40=5+(4*5)+(3*5)

Which makes the first piece equal 5 inches, and the second piece (4x*5) equal 20 inches and the third piece (3x*5) equal 15.

This now makes the problem
40=5+20+15

And you have the final solution of
40=40