2 2/5-(1/4+7/10); 3-( 1/6+2/3); 7-( 2 3/4+7/12);
2 2/5 - (1/4 + 7/10) = 12/5 - (5/20 + 14/20) = 12/5 - 19/20 = 48/20 - 19/20 = 29/20 = 1 9/20 3 - (1/6 + 2/3) = 3 - (1/6 + 4/6) = 3 - 5/6 = 2 1/6 7 - (2 3/4 + 7/12) = 7 - (2 9/12 + 7/12) = 7 - (2 16/12) = 7 - 3 4/12 = 3 8/12 = 3 2/3