Х + 1/8 = 3/5
х = 3/5 - 1/8 Приводим к общему знаменателю 40
х = 24/40 - 5/40
<u>х = 19/40</u>
Проверка:
19/40 + 1/8 = 3/5
19/40 + 5/40 = 24/40
24/40 = 24/40
4-1 5/12=3 12/12-1 5/12= 2 7/12
6 7/15-2 11/15= 5 22/15-2 11/15= 3 11/15;
9 2/21-5 9/21= 8 23/21-5 9/21= 3 14/21= 3 2/3;
11-3 5/12= 10 12/12-3 5/12= 7 7/12;
7 3/20-2 9/20= 6 23/20-2 9/20= 4 14/20= 4 7/10;
6 7/16-2 11/16= 5 23/16-2 11/16= 3 12/16= 3 3/4;
9-5 7/15= 8 15/15-5 7/15= 3 8/15;
8 3/17-3 5/17= 7 20/17-3 5/17= 4 15/17;
10 3/16-3 9/16= 9 19/16-3 9/16= 6 10/16= 6 5/8
1,9-x=2,136:7,12
1,9-x=0,3
x=1,9-0,3
x=1,6
D(a11-a5)/(11-5)=(10-7)/6=0,5
a1=a5-4d=7-2=5
a21=a1+20d=5+10=15