Two Long Straight Parallel Wires Separated by a Distance of 20

Multiple Choice

Two long straight parallel wires separated by a distance of 20 cm carry currents of 30 A and 40 A in opposite directions.What is the magnitude of the resulting magnetic field at a point that is 15 cm from the wire carrying the 30-A current and 25 cm from the other wire?

A) 51 $\mu$ T
B) 33 $\mu$ T
C) 72 $\mu$ T
D) 64 $\mu$ T
E) 46 $\mu$ T