An outdoor swimming race is 1.6 miles long. Simon swims 8 tenths of the course, and his friend Sheila swims 9 tenths of the course. How much farther did Sheila swim?

8 tenths is equal to 8/10, what is equal to 0,8. You can calculate the distance by multiplying 0,8 with the 1,6 mile course. That gives you 1,28 miles. Doing that for Sheila's 9 tenth (0,9) gives you 1,44 miles. That means she swam 1,44-1,28 = 0,16 miles more than Simon.