Find $\frac{8}{7}-\frac{5}{7}$

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{8}{7}-\frac{5}{7}=\frac{8-5}{7}$$=\frac{3}{7}$=0.42

Therefore, $\frac{8}{7}-\frac{5}{7}=\frac{3}{7}$= 0.42.