(Mathematics 5)

Subtraction of fractions with same denominator

Group Activity 6

In pairs:

Get a rectangular cut-out.
Divide the rectangular cut-out into eight equal parts.
Shade seven parts.
Shade again with a different colour three of the shaded parts.
Count the number of parts shaded once.
Discuss your results and share with other groups.

Example 6

Salim was given $\frac{9}{12}$ of a loaf of bread. He gave Juliana $\frac{4}{12}$ of the bread and ate the rest. What fraction of the bread did Salim eat?

Salim had $\frac{9}{12}$ of bread.

He gave Juliana $\frac{4}{12}$ of bread.

Fraction of bread remaining is $\frac{9}{12} - \frac{4}{12} = \frac{9 - 4}{12} = \frac{5}{12} .$

Salim ate $\frac{5}{12}$ of bread.

Note

To subtract fractions with same denominators, subtract the numerators and keep the same denominator.

Exercise F

$\frac{2}{4} - \frac{1}{4} = \frac{}{}$

$\frac{5}{8} - \frac{4}{8} = \frac{}{}$

$\frac{9}{12} - \frac{2}{12} = \frac{}{}$

$\frac{4}{5} - \frac{1}{5} = \frac{}{}$

$\frac{5}{6} - \frac{2}{6} = \frac{}{6} = \frac{}{2}$

$\frac{8}{10} - \frac{3}{10} = \frac{}{10} = \frac{}{2}$

$\frac{11}{12} - \frac{7}{12} = \frac{}{12} = \frac{}{3}$

$\frac{6}{7} - \frac{2}{7} = \frac{}{}$

$\frac{8}{9} - \frac{1}{9} = \frac{}{}$

$\frac{2}{3} - \frac{1}{3} = \frac{}{}$

$\frac{9}{10} - \frac{5}{10} = \frac{}{10} = \frac{}{5}$

$\frac{8}{11} - \frac{4}{11} = \frac{}{}$

Khaemba was given $\frac{7}{8}$ of a cake by the mother. He gave $\frac{3}{8}$ of the cake to the sister.

$\frac{7}{8}$ $\frac{3}{8}$ = $\frac{}{8}$ = $\frac{1}{}$

Natenya had $\frac{9}{10}$ litres of fruit juice. She gave Sadera $\frac{5}{10}$ litres of the fruit juice.

$\frac{9}{10}$ $\frac{5}{10}$ = $\frac{}{10}$ = $\frac{2}{}$

Munjuri withdrew $\frac{5}{7}$ of his salary. He used $\frac{3}{7}$ to buy foodstuff.

$\frac{5}{7}$ $\frac{3}{7}$ = $\frac{}{}$