\(C1:A=\left(5-\dfrac{1}{3}+\dfrac{2}{5}\right)-\left(2-\dfrac{1}{3}+\dfrac{3}{7}\right)-\left(1+\dfrac{2}{5}-\dfrac{3}{7}\right)\)
\(A=\dfrac{76}{15}-\dfrac{44}{21}-\dfrac{34}{35}\)
\(A=2\)
\(C2:A=\left(5-\dfrac{1}{3}+\dfrac{2}{5}\right)-\left(2-\dfrac{1}{3}+\dfrac{3}{7}\right)-\left(1+\dfrac{2}{5}-\dfrac{3}{7}\right)\)
\(A=5-\dfrac{1}{3}+\dfrac{2}{5}-2+\dfrac{1}{3}-\dfrac{3}{7}-1-\dfrac{2}{5}+\dfrac{3}{7}\)
\(A=\left(-\dfrac{1}{3}+\dfrac{1}{3}\right)+\left(\dfrac{2}{5}-\dfrac{2}{5}\right)-\left(\dfrac{3}{7}-\dfrac{3}{7}\right)+\left(5-2-1\right)\)
\(A=0+0-0+3\)
\(A=3\)
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