6,6 = 6 6/10 = 6 3/5
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(2/5 - 6,6) : (- 7/4 - 4/3) = 2 2/185
1) 2/5 - 6,6 = 2/5 - 6 3/5 = - (6 3/5 - 2/5) = - 6 1/5 = - 31/5
2) - 7/4 - 4/3 = - 21/12 - 16/12 = - 37/12
3) - 31/5 : (- 37/12) = - 31/5 * (- 12/37) = 372/185 = 2 2/185