Question

Work out 5/8−2/5 Give your answer in its simplest form.

Answer 1

$\frac{5}{8} - \frac{2}{5}$

First, find the LCD (least common denominator) of the two fractions.
List the multiples of each denominator and find the one that is common.
Multiples of 8: 8, 16, 24, 32, 40
Multiples of 5: 5, 10, 15, 20, 25, 30, 35, 40
40 is your LCD.

Second, what can you divide by to make the denominators of each fraction '40'? Whatever you do to the bottom you must do to the top.
$\frac{5*5}{8*5} - \frac{2*8}{5*8}$

Third, multiply.
$\frac{25}{40} - \frac{16}{40}$

Fourth, since the denominators are the same now, we can combine them.
$\frac{25-16}{40}$

Fifth, subtract '25 - 16' to get 9.
$\frac{9}{40}$

Since $\frac{9}{40}$ is already in the simplest form, it is your answer.

Answer as fraction: $\frac{9}{40}$
Answer as decimal: $0.225$