a: \(=\dfrac{4\left(\dfrac{1}{31}+\dfrac{1}{191}-\dfrac{1}{1115}\right)}{3\left(\dfrac{1}{31}+\dfrac{1}{191}-\dfrac{1}{1115}\right)}+\dfrac{-2\left(\dfrac{1}{11}-\dfrac{1}{19}-\dfrac{1}{357}\right)}{5\left(\dfrac{1}{11}-\dfrac{1}{19}-\dfrac{1}{357}\right)}\)
=4/3-2/5
=20/15-6/15=14/15
b: \(=124\cdot\dfrac{13\left(1-\dfrac{1}{71}-\dfrac{1}{37}-\dfrac{1}{919}\right)}{39\left(1-\dfrac{1}{71}-\dfrac{1}{37}-\dfrac{1}{919}\right)}\cdot\dfrac{39}{62}\)
=39*2*13/39
=2*13=26
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