3 и 1/3 = 10/3
1.9 = 19/10
3 и 1/3 * 1.9 = 10/3 * 19/10 = 190/30 = 19/3
19.5 = 195/10
4 и 1/2 = 9/2
19.5 : 4 и 1/2 = 195/10 : 9/2 = 390/90 = 39/9 = 13/3
Числитель = 19/3 + 13/3 = 32/3
0.16 = 16/100 = 4/25
62/75 - 0.16 = 62/75 - 4/25 = (62 - 12)/75 = 2/3 - знаменатель
32/3 : (2/3) = (32 * 3)/(3 * 2) = 16
X + 4 7\15 = 12 - 5 13\15
X + 4 7\15 = 11 15\15 - 5 13\15 = 6 2\15
X = 6 2\15 - 4 7\15 = 5 17\15 - 4 7\15 = 1 10\15 = 1 2\3
1)140кв.м / 5маш.= 28кв.м 1 машина за 4 часа
2) 28кв.м / 4ч. = 7кв.м в час
3) 63кв.м / 7кв.м = 9 часов
Ответ: 9 часов