Найдите разность смешанных чисел 1). 12 целых 5 девятых минус 7

Найдём разность смешанных чисел:
1) 12 5/9 - 7 1/6 = 113/9 - 43/6 = (113 * 2 - 43 * 3) : 18
= (226 - 129) : 18 = 97/18 = 5 7/18.
2) 7 1/4 - 3 7/15 = 29/4 - 52/15 = (29 * 15 - 52 * 4) : 60 = (435 - 208) : 60 = 227/60 = 3 47/60.
3) 9 5/12 - 6 2/7 = 113/12 - 44/7 = (113 * 7 - 44 * 12) : 84 = (791 - 528) : 84 = 263/84 = 3 11/84.
4) 4 1/6 - 2 4/21 = 25/6 - 46/21 = (25 * 21 - 46 * 6) : 126 = (525 - 276) : 126 = 249/126 = 1 123/126.
5) 5 9/25 - 3 8/15 = 134/25 - 53/15 = (134 * 3 - 53 * 5) : 75 = ( 402 - 265) : 75 = 137/75 = 1 62/75.
6) 4 3/35 - 2 5/14 = 143/35 - 33/14 = (143 * 2 - 33 * 5) : 70 = (286 - 165) : 70 = 121/70 = 1 51/70.
7) 10 3/8 - 4 2/3 = 83/8 - 14/3 = (83 * 3 - 14 * 8) : 24 = (249 - 112) = 137/24 = 6 17/24.