Two Long Parallel Wires Carry Currents Of $20 \mathrm {~A}$ And $5.0 \mathrm {~A}$

Two long parallel wires carry currents of $20 \mathrm {~A}$ and $5.0 \mathrm {~A}$ in opposite directions. The wires are separated by $0.20 \mathrm {~m}$ . What is the strength of the magnetic field midway between the two wires? ( $\left. \mu _ { 0 } = 4 \pi \times 10 ^ { - 7 } \mathrm {~T} \cdot \mathrm { m } / \mathrm { A } \right)$

A) $3.0 \times 10 ^ { - 5 } \mathrm {~T}$
B) $4.0 \times 10 ^ { - 5 } \mathrm {~T}$
C) $2.0 \times 10 ^{- 5} \mathrm {~T}$
D) $1.0 \times 10 ^{- 5} \mathrm {~T}$
E) $5.0 \times 10 ^ { - 5 } \mathrm {~T}$