Tg A=BC/AC, 0.4=x/15, x=BC=6.
1. - 7/5
2. - 7/7 - 2/7 = 5/7
3. - 6 3/5
4. - 2 2/11
5. - 2 5/7
6. - 2 8/8
7. - 3 6/7
8. - 6 = 5+1 = 5 3/3 +1/3 =5 4/3 - 2 1/3 = 3 3/3
9. - 6 21/23
10. - 5=4+1 = 4 11/11+5/11=4 16/11 - 5/11 = 4 11/11
11. - 7=6+1 = 6 7/7+3/7 = 6 10/7 - 2 3/7 = 4 7/7
12. - 5 12/13
13. - 3 3/5
14. 4=3+1 = 3 6/6+1/6 = 3 7/6 - 1/6 = 3 6/6
15. - 8 3/14
1) 88:11/12= 88/1*12/11= 8/1*12/1= 96
2) 162*1 8/81 = 162/1*89/81=2/1*89/1= 178
3) 96+178=274
1)
x + y = 112
x - y = 36
2x = 148 ---------- x = 74
74 - y = 36 ------- y = 38
Ответ: 74 книги на верхней, 38 - на нижней.
2)
x + y = 17
x - y = 7
2x = 24 --------- x = 12
12 - y = 7 ------ y = 5
Ответ: 12 и 5.
3) Альбом - x, тетрадь - y:
7x + 2y = 111
5x + 3y = 84
21x + 6y = 333
10x + 6y = 168
11x = 165 --------- x = 15
75 + 3y = 84 ----- y = 3
Ответ: альбом за 15 рублей, тетрадь - за 3 рубля.