4/9 + 7/63 = 28/63 + 7/63 = 35/63
9 + 2/5 = 45/5 + 2/5 = 47/5
17/18 - 3/9 = 17/18 - 6/18 = 11/18
3 - 14/15 = 75/15 - 14/15 = 61/15
LY: Tự rút gọn (nếu cần)
=28/63+7/63
=35/63
=5/9
45/5+2/5
=47/5
17/18-6/18
=11/18
45/15-14/15
=31/15
9 + 2/5 = 11/5
3 - 14/15 = 31/15
4/9 + 7/63 = 35/63
17/18 - 3/9 = 11/18