(1)5/9 + 3/4= 20+27 / 36 = 47/36=1 11/36
(2)6 7/8 - 3/4= 6 7-6 / 8 = 6 1/8
(3)2/5 + 7/9= 18+35 /45 = 43/45
(4)4 17/18 - 5/9= 4 17-10 / 18 = 4 7/18
(5)4 2/3 * 1 2/7= 14/3 * 9/7 = 2*3=6
(6) 11/12 * 3 3/7 + (3 1/6 - 2 7/15) : 2 6/7=
1) 1/12 * 3 3/7 = 1/12 * 24/7=2/7
2) 3 1/6 - 2 7/15 = 7/6-7/15 = 35-14/30=21/30=7/10
(7) 2 1/7 * 3 1/9=15/7 * 28/9 = 5*4 / 3 =20/3 = 6 2/3