Сравните дроби с число 1/2, а затем между собой 4/5и3/7, 7/13и8/17, 8/17и10/19.
1/2<4/5 4/5>3/7 3/7<7/13<br>1/2>3/7 4/5>7/13 3/7<8/17<br>1/2<7/13 4/5>8/17 3/7<10/19<br>1/2>8/17 4/5>8/17 1/2<10/19 4/5>10/19 8/17=10/19
1 > 3/5 1 < 7/3. 1 > 89/90 1 < 90/89 3/5= 9/15 < 7/3= 35/15 89/90 = 89*89/90*89 = 7921/8010 < 90/89= 90*90/89*90= 8100/8010