Question

- Calcule os números decimais:

a) 7/4 + 3/2 - 0,4 =

b) 2/5 + 0,3 - 1/2 =

c) 0,2 + 1,2 - 3/5 =

d) 0,1 + 0,7 - 3/5 = ​

Answer 1

a)

$= \frac{7}{4} + \frac{3}{2} - \frac{4}{10} \\ = \frac{35}{20} + \frac{30}{20} - \frac{8}{20} \\ = \frac{65 - 8}{20} \\ = \frac{57}{20} \\ = \frac{57 \times 5}{20 \times 5} \\ = \frac{285}{100} \\ = 2.85$

b)

$= \frac{2}{5} + \frac{3}{10} - \frac{ 1}{2} \\ = \frac{4}{10} + \frac{3}{10} - \frac{5}{10} \\ = \frac{2}{10} \\ = 0.2$

c)

$= \frac{2}{10} + \frac{12}{10} - \frac{3}{5} \\ = \frac{14 - 6}{10} \\ = \frac{8}{10} \\ = 0.8$

d)

$= \frac{1}{10} + \frac{7}{10} - \frac{3}{5} \\ = \frac{8}{10} - \frac{6}{10} \\ = \frac{2}{10} \\ = 0.2$