Espressioni

3/7 + (- 2/5 + 1/15)·((3/4 - 1/8)/(7/8) + 5/4 - 1/7) - (- 3/16 + 1/8)/(3/4)=

=3/7 + (- 1/3)·(5/8/(7/8) + 5/4 - 1/7) - (- 1/16)/(3/4)=

=3/7 + (- 1/3)·(5/7 + 5/4 - 1/7) - (- 1/12)=

=3/7 + (- 1/3)·(51/28) + 1/12=

=3/7 - 17/28 + 1/12= 

=- 2/21

157)

$\small \dfrac{3}{7}+\left(-\dfrac{2}{5}+\dfrac{1}{15}\right)·\left[\left(\dfrac{3}{4}-\dfrac{1}{8}\right) : \dfrac{7}{8}+\dfrac{5}{4}-\dfrac{1}{7}\right]-\left(-\dfrac{3}{16}+\dfrac{1}{8}\right) : \dfrac{3}{4}=$

$\small =\dfrac{3}{7}+\left(\dfrac{-6+1}{15}\right)·\left[\left(\dfrac{6-1}{8}\right)·\dfrac{8}{7}+\dfrac{5}{4}-\dfrac{1}{7}\right]-\left(\dfrac{-3+2}{16}\right)·\dfrac{4}{3}=$

$\small =\dfrac{3}{7}+\left(\dfrac{-\cancel5^1}{\cancel{15}_3}\right)·\left[\dfrac{5}{\cancel8_1}·\dfrac{\cancel8^1}{7}+\dfrac{5}{4}-\dfrac{1}{7}\right]-\left(-\dfrac{1}{\cancel{16}_4}\right)·\dfrac{\cancel4^1}{3}=$

$\small =\dfrac{3}{7}-\dfrac{1}{3}·\left[\dfrac{5}{1}·\dfrac{1}{7}+\dfrac{5}{4}-\dfrac{1}{7}\right]+\dfrac{1}{4}·\dfrac{1}{3}=$

$\small =\dfrac{3}{7}-\dfrac{1}{3}·\left[\dfrac{5}{7}+\dfrac{5}{4}-\dfrac{1}{7}\right]+\dfrac{1}{12}=$

$\small =\dfrac{3}{7}-\dfrac{1}{3}·\left[\dfrac{20+35-4}{28}\right]+\dfrac{1}{12}=$

$\small =\dfrac{3}{7}-\dfrac{1}{\cancel3_1}·\dfrac{\cancel{51}^{17}}{28}+\dfrac{1}{12}=$

$\small =\dfrac{3}{7}-\dfrac{17}{28}+\dfrac{1}{12}=$

$\small =\dfrac{36-51+7}{84}=$

$\small =-\dfrac{\cancel8^2}{\cancel{84}_{21}}=$

$\small =-\dfrac{2}{21}$