If 1 mi = 1.6km, how many miles if 112.6?

Basically, proportions are equalities with fractions. If 1 mi. = 1.6 km, then 1mi./1.6km = 1. 

You want to know how many miles are in 112.6 km, that is X mi. = 112.6km. This is your equation. 

Since you already know that 1mi./1.6km = 1, you can multiply the equation by this fraction, and it won't change anything (any number times one is equal to itself, right?). So, X mi. = 112.6km * (1mi/1.6km). Really, all you're doing is dividing 112.6 by 1.6, which is 70.375. 

For your second question, you know that there are 9 people total on court. If there are 2 women, that leaves 7 men. The ratio of women to men is 2 to 7 (or 2/7). 

I hope that helps!