se aduce la acelasi numitor comun pentru toate :
1) 11/5 - 1/10 - 3/10 = (22 - 1 - 3)/10 = 18/10 = 9/5
2)20/3 - 5 /9 - 8/3=(60-5-24)/9= 31/9
3)17/9 +8/3 - 9/9 = (17+24-9)/9= 32/9
4)24/3 -4/6 - 3/2=(48-6-9)/6=33/9
5)31/5 - 5/2 - 3/10=(62-25-3)/10 = 34/10=17/5
6)21/4 + 16/8 - 3/2=(21+8-6)/4 = 23/4
7) 7/2 - 3/2 - 1/3 =(21-9-2)/6 = 10/6=5/3
8)20/2 - 9/3 + 11/6 = (60-18+11)/6 = 52/6 = 26/3
9) 53/10 - 20/100 - 7/50 = (259-10-7)/50 = 242/50=121/25