Find the least common denominator between the two fractions. The least common denominator in this case would be 15, so you have to multiply 1/3 by 5 to have a denominator of 15. Then you multiply 1/5 by 3 to have a denominator of 15. You will find that Mark ran a distance of 2 5/15 km and Shaun ran 3 3/15 km. To make it even easier, you can add the whole number back into the fraction so Mark will have ran 35/15 km and Shaun will have ran 48/15 km meaning that Shaun will have ran more. Then you set you fractions up and subtract them.
