\(\dfrac{4}{5}-\dfrac{3}{5}+\dfrac{1}{4}=\dfrac{1}{5}+\dfrac{1}{4}=\dfrac{4}{20}+\dfrac{5}{20}=\dfrac{9}{20}\)
5/12+3/4+1/3=5/12+9/12+4/12=18/12=3/2
1/4+3/7-11/14=7/28+12/28-11/28=8/28=2/7
4/5-3/5+1/4=1/5+1/4=9/20
5/9+2/3-2=5/9+6/9-18/9=-7/9
\(\dfrac{5}{9}+\dfrac{2}{3}-2=\dfrac{5}{9}+\dfrac{6}{9}-2=\dfrac{11}{9}-2=-\dfrac{7}{9}\)
\(\dfrac{5}{12}+\dfrac{3}{4}+\dfrac{1}{3}=\dfrac{5}{12}+\dfrac{9}{12}+\dfrac{4}{12}=\dfrac{18}{12}=\dfrac{3}{2}\)
\(\dfrac{1}{4}+\dfrac{3}{7}-\dfrac{11}{14}=\dfrac{7}{28}+\dfrac{12}{28}-\dfrac{22}{28}=-\dfrac{3}{28}\)