1. So first of all we have to divide the 3 fractions into decimals to get a decimal to compare. So 5/6 is the same as 5 divided by 6 which is .83 bar and so on...
5/6= .83 bar 1/4= .25 2/3= .66 bar
So 5/6 and 2/3 are closer to one.
2. The two shortest pieces are 2/3 and 1/4 so you se 1/4 + 2/3. Let’s get a common denominator for these fractions. The common denominator is 12. So multiply 1/4 • 3 to get 3/12 and multiply 2/3 by • 4 to get 8/12. Add them together and you get 11/12. So he would need 1/12 more cable or 0.083 bar.
3. Now we have to find a common denominator for all of them. The common denominator is 12 again. Multiply 5/6•2 and then you get 10/12, then add 10/12 +2/12(from 1/4) and then you get leftover with 9/12 or 3/4 more wire.
