Need help with practice problem

A current of 0.76 A flows through a copper wire 0.44 mm in diameter when it connected to a potential difference of 15 V. Find: 1- The resistance of the wire 2- The length of the wire {the value of the p for copper is 1.72 x 108 0.m} 3- If the wire heated to 50 and the potential difference (15 V) maintained. What is the resultant current in the wire? (a=3.9x10-3 (C)-1)