\(\dfrac{2}{20}-\dfrac{-3}{36}+\dfrac{4}{60}=\dfrac{1}{4}\)
\(\dfrac{2}{20}-\left(-\dfrac{3}{36}\right)+\dfrac{4}{60}\\ =\dfrac{1}{10}+\dfrac{1}{12}+\dfrac{1}{15}\\ =\dfrac{6}{60}+\dfrac{5}{60}+\dfrac{4}{60}\\ =\dfrac{6+5+4}{60}\\ =\dfrac{15}{60}\\ =\dfrac{1}{4}\)
\(\dfrac{2}{20}-\left(-\dfrac{3}{36}\right)+\dfrac{4}{60}=\dfrac{2}{20}+\dfrac{3}{36}+\dfrac{4}{60}=\dfrac{1}{10}+\dfrac{1}{12}+\dfrac{1}{15}=\dfrac{6}{60}+\dfrac{5}{60}+\dfrac{4}{60}=\dfrac{15}{60}=\dfrac{1}{4}\)
\(\dfrac{2}{20}-\dfrac{-3}{36}+\dfrac{4}{60}\)
\(20=2^2.5\\ 36=2^2.3^2\\ 60=2^2.3.5\)
BCNN(20;36;60)=22.32.5=180
\(\Rightarrow=\dfrac{18}{180}-\dfrac{-15}{180}+\dfrac{12}{180}=\dfrac{18-\left(-15\right)+12}{180}=\dfrac{45}{180}\)
\(=\dfrac{1}{10}-\dfrac{-1}{12}+\dfrac{4}{60} =\dfrac{6}{60}+\dfrac{5}{60}+\dfrac{4}{60} =\dfrac{6+5+4}{60} =\dfrac{15}{60}=\dfrac{1}{4}\)