Удимы и саши было 57о тенге, на 1/4 своих денег дима купил альбом, а саша на1/6 своих денег купил книгу. после этого у каждого из них осталось одинаковая сумма денег. сколько денег было у димы первоначально?

х-1/4х=3/4х-осталось у димы.

(570--х): 6=5*(570-х): 6-осталось у саши.

1)3/4х=5*(570-х): 6

18х=20*(570-х)

18х+20х=11400

38х=11400

х=11400: 38

х=300тенге-было у димы.

2)570-300=270тенге-было у саши. 

объяснение:

my daily routine

as a rule, i get up at half past six. i put on my dressing-gown, go into bathroom and turn on the bath taps. good health is better than wealth, so i do my morning exercises. i get breakfast at seven-thirty and listen to the news over the radio.

i like to begin the day well, so my breakfast is always a good one. for breakfast i usually have hard-boiled eggs or an omelette, bread and butter, tea or coffee; i read my newspaper with my last cup of coffee before i leave home.

then, i say "good-bye" to my mother, take my school-bag and go to school. i don't live far from my school, so it doesn't take me long to get there. the lessons start at half past eight. each lesson lasts for 45 minutes. the classes are over at two o'clock.

i come back home, have dinner, wash up and go shopping. i buy foodstuffs for the family. coming back i begin to clean the house and get the vegetables ready for supper. we have supper at seven. i do my homework for the next day. it usually takes me several hours to prepare well for the lessons.

in the evening, i always try to spend at least an hour at the piano. as a rule my parents and i sit and talk, watch a film on tv, read newspapers and magazines. sometimes, we go to the cinema or to the theatre. once or twice a month, i visit exhibitions in my home town.

i go to bed at about eleven o'clock, but my parents like to sit up late and write letters or read.

Допустим, что скорость течения реки равна х км/ч, тогда по течению лодка будет идти со скоростью 15 + х км/ч, а против течения со скоростью 15 - х км/ч.

По условию задачи составим уравнение:

24/(15 + х) + 2/3 = 24/(15 - х),

(102 + 2 * х)/(45 + 3 * х) = 24/(15 - х),

- 2 * х² - 144 * х + 450 = 0

Дискриминант данного уравнения равен:

(-144)² - 4 * (- 2) * 450 = 24336.

Так как х может быть только положительным числом, уравнение имеет единственное решение:

х = (144 - 156)/-4 = 3 (км/ч) - скорость течения реки.