1) х+215=612
х=612-215
х=397
2)500-х=346
х=500+346
х=846
3)х-485=197
х=485+197
х=682
1) 2 4/7+4 3/5 =2 20/35+4 21/35 =6 41/35= 7 6/35. 2) 7 1/2 -4/5 = 7 5/10 -8/10 = 75/10 -8/10= 67/10 = 6 7/10. 3) 3 2/7 -4/5 = 3 10/35 -28/35 = 115/35 -28/35 =87/35=2 17/35.
1) 0.4(x-3)=0.5(4+x)-2.5
0.4x-1.2=2+0.5x-2.5
0.4x-1.2=-0.5+0.5x
0.4x-0.5x=-0.5+1.2
-0.1x=0.7
x=-7
Ответ : 190 натуральных чисел