1) (2 4/9+1 1/6)*1 4/5-3 1/9÷2 1/3 = ((2+1)+(4/9 + 1/6)) * 4/5 - 28/9 : 7/3 = (3+11/18) * 4/5 - 28/9 * 3/7 = 3 11/18 * 4/5 - 4/3 = 65/18 * 4/5 - 4/3 13/9 * 2 - 4/3 = 26/9 - 4/3 = 14/9
2)(2-1 7/12)÷(3/8-1/6)*3 1/4 = (2 - 19/12) : 5/24 * 13/4 = 5/12 * 24/5 * 13/4 = 2 * 13/4 = 13/2
3)(7/10-2/5)*(1/4+5/6)÷6 1/2 = 3/10 * 13/12 : 13/2 = 1/10 * 13/4 * 2/13 = 1/5 * 1/5 = 1/20