1) 3/7 (1/3 + 4/9) = 3/7 (3/9 + 4/9) = 3/7 * 7/9 = 21/63 + 28/63 = 49/63
2) 4/5 - 1/4 : 5/6 = 4/5 - 1/4 * 6/5 = 4/5 - 6/20 = 16/20 - 6/20 = 10/20 = 1/2
1) 3/7 (1/3 + 4/9) = 3/7 (3/9 + 4/9) = 3/7 * 7/9 = 21/63 + 28/63 = 49/63
2) 4/5 - 1/4 : 5/6 = 4/5 - 1/4 * 6/5 = 4/5 - 6/20 = 16/20 - 6/20 = 10/20 = 1/2