1 length is 4.75 feet
42 lengths = x feet Cross multiply
1 * x = 42 * 4.75 Multiply on the right
x = 199.5
amount left = amount started with - amount amount used
Amount left = ???
Amount started with = 240 feet.
Amount used = 199.5 Substitute
Amount left = 240 - 199.5 Subtract
Amount left = 40.5 Answer