a: =-1/21-3/21=-4/21
b: =-20/36-3/36=-23/36
c: =37/5+7/5=44/5
d: 12/3-2/3=10/3
e: =-3/7+10/7-4=1-4=-3
\(a=-\dfrac{1}{21}-\dfrac{3}{21}=-\dfrac{4}{21}\)
\(b=-\dfrac{20}{36}-\dfrac{3}{36}=-\dfrac{23}{36}\)
\(c=\dfrac{37}{5}+\dfrac{7}{5}=\dfrac{44}{5}\)
\(d=\dfrac{12}{3}-\dfrac{2}{3}=\dfrac{10}{3}\)
\(e=-\dfrac{3}{7}+\dfrac{10}{7}-4=\dfrac{7}{7}-4=1-4=-3\)
\(f=\dfrac{1}{15}+\dfrac{1}{4}+\dfrac{14}{15}+\dfrac{3}{4}-1,5=\left(\dfrac{1}{15}+\dfrac{14}{15}\right)+\left(\dfrac{1}{4}+\dfrac{3}{4}\right)-1,5\\ =1+1-1,5=0,5\)
\(g=-\dfrac{2}{3}.\dfrac{-4}{5}=\dfrac{2}{3}.\dfrac{4}{5}=\dfrac{8}{15}\)
\(h=\left(-\dfrac{1}{5}\right).\dfrac{9}{2}=\dfrac{-9}{10}\)
\(i=-\dfrac{15}{4}:-\dfrac{21}{10}=\dfrac{15}{4}.\dfrac{10}{21}=\dfrac{25}{14}\)
\(j=-\dfrac{5}{14}.\left(\dfrac{17}{19}+\dfrac{2}{19}\right)+\dfrac{5}{14}=-\dfrac{5}{14}.1+\dfrac{5}{14}=-\dfrac{5}{14}+\dfrac{5}{14}=0\)
\(k=\dfrac{15}{23}.\dfrac{7}{19}+\dfrac{12}{19}.\dfrac{15}{23}=\left(\dfrac{7}{19}+\dfrac{12}{19}\right).\dfrac{15}{23}=1.\dfrac{15}{23}=\dfrac{15}{23}\)
\(l=\left(31\dfrac{4}{18}-30\dfrac{4}{18}\right)+\left(-\dfrac{5}{12}+\dfrac{17}{12}\right)=1+1=2\)
\(m=-\dfrac{5}{7}.\dfrac{19}{17}+\dfrac{-5}{7}.\dfrac{-2}{17}+\dfrac{12}{17}=-\dfrac{5}{7}.\left(\dfrac{19}{17}+\dfrac{-2}{17}\right)+\dfrac{12}{17}=-\dfrac{5}{7}.1+\dfrac{12}{17}\\ =-\dfrac{5}{7}+\dfrac{12}{7}=1\)
\(n=1+\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{99}-\dfrac{1}{100}\\ =1+\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{100}=1+1-\dfrac{1}{100}=2-\dfrac{1}{100}\\ =\dfrac{199}{100}\)
\(o=-3,8+\left(-5,7\right)+3,8=\left(-3,8+3,8\right)+\left(-5,7\right)=0-5,7=-5,7\)
\(p=3,1-2,5+2,5-3,1=\left(3,1-3,1\right)+\left(-2,5+2,5\right)=0+0=0\)
