The copper wire was 150 meters longer than the steel wire. You take 240-60 and get 180. You can then divide that number by 2 to figure out how long the steel wire was to get 90. From there, subtract the 90 by the original 240 and you’ll get 150.
150 meters longer at first, because you would do 240 minus the 60 cut off and divide that by two, which gives you 90, the length of the second wire. then subtract 90 from 240