S/(X-2,5)=2,5
S/(X+2,5)=2
2,5*X-6,25=2*X+5
0,5*X=11,25
X=22,5
S=2*X+5
S=45+5=50
Ответ: 50 км
20/27 * 3/5 + 1/10 : 3/100 = 3 7/9
20/27 * 3/5 + 1/10 : 3/100 = 4/9 + 1/10 : 3/100 = 4/9 + 1/10 * 100/3 = 4/9 + 10/3
НОК(9,3) = 9
(4*1 + 10*3)/9 = (4 + 30)/9 = 34/9 = 3 7/9
3/4 ÷ 9/16 - 5/8 * 4/15 = 1 1/6
3/4 ÷ 9/16 - 5/8 * 4/15 = 3/4 * 16/9 - 5/8 * 4/15 = 4/3 - 5/8 * 4/15 = 4/3 - 1/6
НОК(3,6) = 6
(4*2 - 1*1)/6 = (8 - 1)/6 = 7/6 = 1 1/6
1)6+х=13
Х=13-6
Х=7
__________
6+7=13
13=13
2)13-х=5
Х=13-5
Х=8
___________
13-8=5
5=5
3)Х+7=12
Х=12-7
Х=5
__________
5+7=12
12=12