Understand Fraction Addition and Subtraction Practice Test

Jake had $$\frac{7}{10}$$ of his homework completed. After working for 30 minutes, he finished $$\frac{2}{10}$$ more of his homework. Now Jake realizes he made an error and needs to undo $$\frac{1}{10}$$ of the work he just completed. What fraction of his homework does Jake have completed now?

A recipe calls for $$\frac{3}{5}$$ cup of flour. Sarah has already added $$\frac{1}{5}$$ cup of flour to her mixing bowl. She wants to know how much more flour she needs to add. Which statement best explains the subtraction $$\frac{3}{5} - \frac{1}{5}$$?