Question

Вычислите .
а) 7/15 - 3/5
b) 5/7 + 9/77
c)5/42 - 8/24+1/8
d) - 1/32 - 29/40
e) 9/13- 5/26 × 4/9
f) 7/9:5+4/5×7/8
​

Answer 1

$a) \: \frac{7}{15} - \frac{3}{5} = \frac{7}{15} - \frac{9}{15} = - \frac{2}{15}$

$b) \: \frac{5}{7} + \frac{9}{77} = \frac{11}{77} + \frac{9}{77} = \frac{20}{77}$

$c) \: \frac{5}{42} - \frac{8}{24} + \frac{1}{8} = \frac{5}{42} - \frac{1}{3} + \frac{1}{8} = \frac{20 - 56 + 21}{168} = - \frac{ 15}{168} = - \frac{5}{56}$

$d) \: - \frac{1}{32} - \frac{29}{40} = - \frac{5 + 116}{160} = - \frac{121}{160}$

$e) \: \frac{9}{13} - \frac{5}{26} \times \frac{4}{9} = \frac{9}{13} - \frac{5}{13} \times \frac{2}{9} = \frac{9}{13} - \frac{10}{117} = \frac{71}{117}$

$f) \: \frac{7}{9} \div 5 + \frac{4}{5} \times \frac{7}{8} = \frac{7}{9} \times \frac{1}{5} + \frac{1}{5} \times \frac{7}{2} = \frac{7}{45} + \frac{7}{10} = \frac{77}{90}$