Simple. First, you must know how long a yard is(3ft). Next, multiply that by 2 because there are 2 yards for each piece. That will give you 6ft for each piece of wire. Now you must multiply 7 by 6 which gives you 42. After that multiply the 6 in the word problem by the 3 in the word problem. This gives you 18. Subtract 18 from 42(42-18) and you will have your answer.