Chapter 26.8, Problem 26.8GI

The figure shows three parallel wires carrying current of the same magnitude I, but in one of them the current direction is opposite that of the other two. If ${\displaystyle \oint \stackrel{\to }{B}}\cdot d\stackrel{\to }{l}\ne 0$ around loop 2, (1) what’s ${\displaystyle \oint \stackrel{\to }{B}}\cdot d\stackrel{\to }{l}$ around loop 1, and (2) which current is the opposite one?