Ответ:\(5.7+(8.1−4.7)=5.7+3.4=9.1\).\(3.39−(1.39−4.5)=3.39−(−3.11)=3.39+3.11=6.5\).\(3.7−(−5.3+3.7)=3.7−(−1.6)=3.7+1.6=5.3\).Ответ: 1) 9,1; 2) 6,5; 3) 5,3.