1) 3,48 * 75/116 = 348/100 * 75/116 = 9/4 = 2 1/4

2) 10 1/7 - 2 1/4 = 10 4/28 - 2 7/28 = 7 25/28

3) 7 25/28 : 31 4/7 = 221/28 : 221/7 = 221/28 * 7/221 = 1/4

ответ: 1/4