A, X:3/5+4/3=5/6
⇔ X:3/5 = -1/2
⇔ X = -3/10
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B, X:(3/5+4/3)=5/6
⇔ X:29/15 = 5/6
⇔ X = 29/18
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C,(X+3/5):4/3=5/6
⇔X+3/5 = 10/9
⇔ X = 23/45
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D, X.1212/1515-X.1919/2020=6/-5
⇔ -3/20X = -6/5
⇔ X = 8