Two wires, where is magentic field zero?

[FuzzyDunlop]

Homework Statement

Two wires carry current I1 = 53 A and I2 = 37 A in the opposite directions parallel to the x-axis at y1 = 3 cm and y2 = 13 cm. Where on the y-axis (in cm) is the magnetic field zero?

I1= 53 A
I2=37A

Homework Equations

B(r)=Iu/[2(pi)r]

The Attempt at a Solution

I thought i could solve this guy by setting the strengths of the fields equal to each other and finding r. Much of it would cancel out so I basically had

53u/(2[pi]r)=37u/(2[pi](10-r)

[(10-r)*53]/r=37

r=5.88

and then I added 3 to r since the starting position is y=3. It made sense to me but obviously i messed up somewhere.

 

[LowlyPion]

If the current in the wires is going in opposite directions what do the field vectors do in the distance between the 2 wires?