Evaluate $\frac{5}{9}+\frac{8}{9}$59+89.

Write your answer in its simplest form.

Evaluate $\frac{5}{9}-\frac{4}{9}$59−49.

Evaluate $\frac{4}{21}+\frac{8}{21}$421+821.

Evaluate $\frac{9}{28}-\frac{3}{28}$928−328.

Understand addition and subtraction of fractions, decimals, and integers