The question had stated that there exists a certain amount of grams in ounce and also a certain amount of pounds in a kilogram. The error of Miriam most likely came from conversion error. She probably did a ounces to kilograms conversion, instead of a kilograms to ounces conversion that was asked of her.
You can find the slope of an equation by looking at what number comes before x. Making the slope being -1/2 because that's the number that comes before x.
