A1.5m wire carries a 8 a current when a potential difference of 57 v is applied. what is the resistance of the wire?

In order to obtain the resistance of the wire we can use the Ohm's law which states that the current through a conductor between two points is directly proportional to the voltage across the two points.
I=V/R 
We know that the current is 8A , I=8A and we also know the potential difference, which is the voltage, V=57 V.
The length of the wire does not play any role, has not influence.
So,
R is the resistance and from I=V/R , R=V/I
R=57/8=9 Ohms. The resistance is 9 Ohms.