Two sides of a triangle have lengths for yard and 7 yard describe the possible lengths of the third side

Suppose "for yard" means "four yard", so the side lengths are 4 and 7 yards.

The triangle inequality rule says that the sum of the two shorter sides of a triangle must be greater than the third side.
Therefore if the third side x is the shortest side, then x+4>7, or x>7-4=3 yards.
If the third side x is the longest side, then 4+7>x, or x<11 yards.
Therefore the length of the third side must be greater than 3 yards, and less than 11 yards.