Clean, printable math worksheet featuring 15 problems for practicing addition and subtraction of fractions with unlike denominators.

Here are the step-by-step solutions for each problem on the worksheet.

1) $\frac{4}{3} + \frac{2}{5}$
* Find a common denominator for 3 and 5, which is 15.
* Convert fractions: $\frac{4 \times 5}{3 \times 5} = \frac{20}{15}$ and $\frac{2 \times 3}{5 \times 3} = \frac{6}{15}$.
* Add: $\frac{20}{15} + \frac{6}{15} = \frac{26}{15}$.
* Convert to mixed number: $1 \frac{11}{15}$.

2) $\frac{7}{10} - \frac{2}{5}$
* The common denominator for 10 and 5 is 10.
* Convert $\frac{2}{5}$: $\frac{2 \times 2}{5 \times 2} = \frac{4}{10}$.
* Subtract: $\frac{7}{10} - \frac{4}{10} = \frac{3}{10}$.

3) $\frac{5}{9} + \frac{2}{7}$
* Common denominator for 9 and 7 is 63.
* Convert fractions: $\frac{5 \times 7}{9 \times 7} = \frac{35}{63}$ and $\frac{2 \times 9}{7 \times 9} = \frac{18}{63}$.
* Add: $\frac{35}{63} + \frac{18}{63} = \frac{53}{63}$.

4) $\frac{4}{8} - \frac{1}{4}$
* Simplify $\frac{4}{8}$ to $\frac{1}{2}$. Now solve $\frac{1}{2} - \frac{1}{4}$.
* Common denominator is 4. Convert $\frac{1}{2}$ to $\frac{2}{4}$.
* Subtract: $\frac{2}{4} - \frac{1}{4} = \frac{1}{4}$.
* *(Alternatively, keep $\frac{4}{8}$ and convert $\frac{1}{4}$ to $\frac{2}{8}$. $\frac{4}{8} - \frac{2}{8} = \frac{2}{8}$, which simplifies to $\frac{1}{4}$.)*

5) $\frac{3}{9} + \frac{1}{3}$
* Simplify $\frac{3}{9}$ to $\frac{1}{3}$.
* Add: $\frac{1}{3} + \frac{1}{3} = \frac{2}{3}$.

6) $\frac{2}{5} + \frac{1}{10}$
* Common denominator is 10. Convert $\frac{2}{5}$ to $\frac{4}{10}$.
* Add: $\frac{4}{10} + \frac{1}{10} = \frac{5}{10}$.
* Simplify: $\frac{1}{2}$.

7) $\frac{4}{5} + \frac{9}{10}$
* Common denominator is 10. Convert $\frac{4}{5}$ to $\frac{8}{10}$.
* Add: $\frac{8}{10} + \frac{9}{10} = \frac{17}{10}$.
* Convert to mixed number: $1 \frac{7}{10}$.

8) $\frac{4}{6} - \frac{1}{3}$
* Simplify $\frac{4}{6}$ to $\frac{2}{3}$.
* Subtract: $\frac{2}{3} - \frac{1}{3} = \frac{1}{3}$.

9) $\frac{3}{12} + \frac{2}{4}$
* Simplify $\frac{3}{12}$ to $\frac{1}{4}$.
* Add: $\frac{1}{4} + \frac{2}{4} = \frac{3}{4}$.

10) $\frac{5}{12} - \frac{1}{6}$
* Common denominator is 12. Convert $\frac{1}{6}$ to $\frac{2}{12}$.
* Subtract: $\frac{5}{12} - \frac{2}{12} = \frac{3}{12}$.
* Simplify: $\frac{1}{4}$.

11) $\frac{2}{8} + \frac{3}{9}$
* Simplify first: $\frac{2}{8} = \frac{1}{4}$ and $\frac{3}{9} = \frac{1}{3}$.
* Problem becomes $\frac{1}{4} + \frac{1}{3}$. Common denominator is 12.
* Convert: $\frac{3}{12} + \frac{4}{12} = \frac{7}{12}$.

12) $\frac{1}{4} - \frac{1}{8}$
* Common denominator is 8. Convert $\frac{1}{4}$ to $\frac{2}{8}$.
* Subtract: $\frac{2}{8} - \frac{1}{8} = \frac{1}{8}$.

13) $\frac{6}{7} + \frac{2}{6}$
* Simplify $\frac{2}{6}$ to $\frac{1}{3}$. Problem is $\frac{6}{7} + \frac{1}{3}$.
* Common denominator is 21.
* Convert: $\frac{6 \times 3}{21} + \frac{1 \times 7}{21} = \frac{18}{21} + \frac{7}{21}$.
* Add: $\frac{25}{21}$.
* Convert to mixed number: $1 \frac{4}{21}$.

14) $\frac{1}{3} - \frac{1}{7}$
* Common denominator is 21.
* Convert: $\frac{7}{21} - \frac{3}{21}$.
* Subtract: $\frac{4}{21}$.

15) $\frac{7}{8} + \frac{4}{5}$
* Common denominator is 40.
* Convert: $\frac{7 \times 5}{40} + \frac{4 \times 8}{40} = \frac{35}{40} + \frac{32}{40}$.
* Add: $\frac{67}{40}$.
* Convert to mixed number: $1 \frac{27}{40}$.

Final Answer:
1) $1 \frac{11}{15}$
2) $\frac{3}{10}$
3) $\frac{53}{63}$
4) $\frac{1}{4}$
5) $\frac{2}{3}$
6) $\frac{1}{2}$
7) $1 \frac{7}{10}$
8) $\frac{1}{3}$
9) $\frac{3}{4}$
10) $\frac{1}{4}$
11) $\frac{7}{12}$
12) $\frac{1}{8}$
13) $1 \frac{4}{21}$
14) $\frac{4}{21}$
15) $1 \frac{27}{40}$