630=2*5*3*3*7
252=2*2*3*3*7
НОД=2*3*3*7=126
НОК= 2*5*3*3*7*2=1260
252/630=2/5
29/252+17/630=145/1260 +34/1260 =179/1260
5/14+10/21=15/42+20/42 = 35/42
35/42*18/5 = 3
13/22- 25/33 = 39/66-50/66= - 11/66 = -1/6
1 1/6: (-1/6 = 7/6*(-6/1 = -7
3+(-7) = 3-7=-4