Find $\frac{5}{7}-\frac{2}{7}$

When subtracting fractions, the denominators (the bottom numbers) must be the same. In this case, both fractions have a denominator of 7. Subtract the numerators (the top numbers) and keep the denominator the same.
 So, it is, $\frac{5}{7}-\frac{2}{7}=\frac{5-2}{7}=\frac{3}{7}$

Therefore, $\frac{5}{7}-\frac{2}{7}=\frac{3}{7}$.