Adding & Subtracting Fractions (Same Denominator)

≈ 20 min

When two fractions have the same denominator, they are made of pieces the same size, so you simply add (or subtract) the numerators and keep the denominator:

\frac{2}{7} + \frac{3}{7} = \frac{2+3}{7} = \frac{5}{7}, \qquad \frac{5}{8} - \frac{1}{8} = \frac{4}{8} = \frac{1}{2}.

Always check whether the answer can be simplified, as in $\frac{4}{8} = \frac{1}{2}$ above.

What is $\dfrac{2}{7} + \dfrac{3}{7}$ ?

$\dfrac{5}{7}$

$\dfrac{5}{14}$

$\dfrac{6}{7}$

$\dfrac{1}{7}$

Work out $\dfrac{5}{8} - \dfrac{1}{8}$ and give the answer in simplest form, as a fraction like a/b.

A pizza is cut into $12$ equal slices. You eat $5$ slices and your friend eats $3$ . How many twelfths of the pizza have been eaten in total? (Give the number of slices.)

A $10$ -litre bucket is $\dfrac{7}{10}$ full. You pour out $\dfrac{3}{10}$ of a bucket. What fraction is left? Give the answer in simplest form, as a fraction like a/b.