Question

Calculati a) 7 supra 20 - 5 supra 18. b) 8 supra 13 - 5 supra 39. c)3-2 supra 5. dau coronita celui mai bun raspuns

Answer 1

$a) \frac{7}{20} - \frac{5}{18} = \frac{7 \times 9}{20 \times 9} - \frac{5 \times 10}{18 \times 10} = \frac{63}{180} - \frac{50}{180} = \frac{63 - 50}{180} = \frac{13}{180}$

$b) \frac{8}{13} - \frac{5}{39} = \frac{8 \times 3}{13 \times 3} - \frac{5}{39} = \frac{24}{39} - \frac{5}{39} = \frac{24 - 5}{39} = \frac{19}{39}$

$c)3 - \frac{2}{5} = \frac{3}{1} - \frac{2}{5} = \frac{3 \times 5}{1 \times 5} - \frac{2}{5} = \frac{15}{5} - \frac{2}{5} = \frac{15 - 2}{5} = \frac{13}{5} = 2 \frac{3}{5}$