Question

Цену ручки снизили на 15%, а затем новую цену снизили еще на20%. стоимомость ручки оказалось равной 13.600 рублей. найти первоночальную стоимость

Answer 1

15 % = 0,15 
20 % = 0,2 
1) 1 - 0,15 = 0,85 ( цены ) после первого снижения 
2) 0,85 * ( 1 - 0,2 ) = 0,85 * 0,8 = 0,68 ( цены ) после второго снижения 
3) 13600 : 0,68 = 20000 ( руб )
ОТВЕТ 20000 рублей 

Answer 2

Calculation of the Initial Cost of the Pen

To find the initial cost of the pen, we need to work backwards from the final cost of 13,600 rubles. We know that the price of the pen was first reduced by 15%, and then the new price was further reduced by 20%.

Let's denote the initial cost of the pen as x.

The first reduction of 15% can be calculated by subtracting 15% of x from x: x - 0.15x = 0.85x

The second reduction of 20% can be calculated by subtracting 20% of the new price (0.85x) from the new price: 0.85x - 0.20(0.85x) = 13,600

Now we can solve this equation to find the initial cost of the pen (x).

Solving the Equation

Let's solve the equation to find the value of x:

0.85x - 0.17x = 13,600

Simplifying the equation:

0.68x = 13,600

Dividing both sides of the equation by 0.68:

x = 13,600 / 0.68

Calculating the value of x:

x = 20,000

Therefore, the initial cost of the pen was 20,000 rubles.

Conclusion

The initial cost of the pen was 20,000 rubles.