Convert 7.7km into miles if 1.6 km = 1 mile

This is a simple equation.  

The equation is y = 1.6x  with y being the miles and x being the kilometers.

Lets plug the kilometers in.

Y=1.6(7.7)

1.6 *  7.7 = 12.32

12.32 miles is  equal to 7.7 kilometers

HOWEVER

There are about .6 miles in a kilometer, so if you typed this wrong I don't know.  

It is still the same concept.

Y = .6x

Y = .6(7.7)

.6 * 7.7 =  4.8

In this case there are 4.8 miles in 7.7 kilometers

The answer is part a: use