"/" - это типо палка дроби
1) 18/45 = 2·9/5·9 = 2/5
2) 22/88 = 1·22/4·22 = 1/4
3) 12/36 = 1·12/3·12 = 1/3
4) 50/75 = 2·25/3·25 = 2/3
5) 30/105 = 2·15/7·15 = 2/7
6) 400/500 = 4·100/5·100 = 4/5
7) 88/990 = 4·22/45·22 = 4/45
8) 42/720 = 7·6/120·6 = 71/120
9) 100/25 = 4·25/25 = 4
10) 24/360 = 1·24/15·24 = 1/15