She has given recently are different length one is 3 4/5 feet long and the other is 3 1/2 feet long how much would she have to cut so it will be the same length

So here you want to convert both of these numbers until they have the same denominator.

The LCM of the two is 10, so the closest same denominator of the 3 4/5 and 3 1/2 is 10.

3 4/5 -> 3 8/10

3 1/2 -> 3 5/10

The difference between the two is 3/10 feet.

She will have to cut 3/10 feet of the 3 4/5 length rope for the two to be the same length.