A)7/12 б)2/5 в)13/20
(4/6)/2=2/3; 2/3=2/3
а)250/1000=1/4т
б)25/60=5/12м
в)16/24=2/3с
г)200/1000=1/5км
х=3:9/15=3*15/9=15/3=5
1/4=10/40
7/8=35/40
11/20=22/40
[-7;13]- -6,-5,-4,-3,-2,-1,0,1,2,3,4,5,6,7,8,9,10,11,12.
403(385-86)+299*597=403*299+299*597=
299(403+597)=299000
1) (2d)*(2*(d:3))=2d*(2d:6)
2)(k:3)*2
3) d:10
1) 2 1/7 : 15 = 15/7 * 1/15 = 1/7
2) 1 7/9 : 8 = 16/9 * 1/8 = 2/9
3) 4 1/2 : 6 = 9/2 * 1/6 = 3/4
4) 5 1/4 : 7 = 21/4 * 1/7 = 3/4