900-х=200. а+300=800-100
-х=200-900. а=700-300
-х=-700. а=400
х=700. ответ:400
ответ:700
1) 5 3/10
2) 0 7/100
3) 15 9/10
4) 101 1/100
5) 237 71/1000
6) 89 5/1000
7) 18 404/10000
8) 901 901/10000
9) 1000 1/10000
1/6+x=2/9 x:2 2/5=3/4
x=2/9-1/6 x:12/5=3/4
x=-5/18 x•5/12=3/4
5/12x=3/4
x=9/5
(2 4/15-1 5/12 ) : 3 2/5 +1/8=(34/15-17/12):17/5+1/8=17/20:5/17+1/8=1/4+1/8=3/8