PHYSICS!!!
posted by OLLIJURT .
A long wire carrying a 5.0 A current perpendicular to the xyplane intersects the xaxis at x = 2.0 cm. A second, parallel wire carrying a 2.5 A current intersects the xaxis at x = 2.0 cm.
PART A
At what point on the xaxis is the magnetic field zero if the two currents are in the same direction?
PART B
At what point on the xaxis is the magnetic field zero if the two currents are in opposite directions?

I don't understand !!! after Physics.
part A is biotsavart problem, add the two magnetic fields to be zero, you know the total distance, currents.
partB. Same law. You know it wont be between the wires. 
part a is 0.67cm