Question

: Оля решила купитьдвекниги: первая стоит 56 %,всехееденег, авторая- 64 %,и поэтому у неенехватило на покупку этих книг15 р. Сколько стоят эти книги вместе?

Answer 1

У Оли х руб
первая книга стоит 0.56х
вторая книга стоит 0.64х
0.56х + 0.64х - 15 = х
0.2х = 15
х = 75
книги вместе стоят 75+15 = 90 руб
ПРОВЕРКА: у Оли 75 руб
первая книга стоит 75*0.56 = 42 руб
вторая книга стоит 75*0.64 = 48 руб
две книги стоят 48+42 = 90 руб ---это на 15 руб больше, чем есть у Оли...

Answer 2

                    
|_____________|_______|_______________|
                               20%                                  100%
1)100%-56%=44%-остаток денег после предполагаемой покупки 1-ой книги
2)64%-44%=20%- составляют 15 руб.
3)15:20%*100%=75(руб)-все деньги Ольги
4)75+15=90(руб)-стоимость двух книг

Answer 3

Problem Analysis

Оля wants to buy two books, but she doesn't have enough money. The first book costs 56% of the total amount she has, and the second book costs 64% of the total amount. She is short of 15 rubles to buy both books. We need to find the total cost of the two books.

Solution

Let's assume the total amount of money Olya has is x rubles.

According to the problem, the first book costs 56% of the total amount, which is 0.56x rubles.

The second book costs 64% of the total amount, which is 0.64x rubles.

The total cost of the two books is the sum of the cost of the first book and the cost of the second book.

So, the equation can be written as:

0.56x + 0.64x = x + 15

Now, let's solve this equation to find the value of x.

0.56x + 0.64x = x + 15

Combining like terms:

1.2x = x + 15

Subtracting x from both sides:

0.2x = 15

Dividing both sides by 0.2:

x = 15 / 0.2

Simplifying:

x = 75

Therefore, Olya has 75 rubles.

To find the total cost of the two books, we substitute the value of x back into the equation:

0.56x + 0.64x = 75 + 15

Calculating:

0.56 * 75 + 0.64 * 75 = 42 + 48 = 90

Therefore, the total cost of the two books is 90 rubles.

Answer

The total cost of the two books is 90 rubles.