Question

за 4 карандаша и 3 ручки заплатили 70 руб за 2 таких же карандаша и1 ручку заплатили 28 руб сколько стоит 1 карандаш и сколько стоит 1 ручка

Answer 1

Решение
1) 28*2=56 (руб.) - стоят 4 карандаша и 2 ручки (2*(2к+1р)=2*28).
2) 70-56=14 (руб.) - стоит одна ручка (4к+3р-4к-2р = 1 р)
3) 28-14=14 (руб.) - стоят два карандаша (2к+1р=2к+14=28; 2к=28-14)
4) 14:2=7 (руб.) - стоит один карандаш.
ОТВЕТ: один карандаш стоит 7 рублей, одна ручка стоит 14 рублей.

к→карандаш
р→ручка

Answer 2

Problem Analysis

We are given the information that 4 pencils and 3 pens were purchased for a total of 70 rubles. Additionally, 2 pencils and 1 pen were purchased for a total of 28 rubles. We need to determine the cost of 1 pencil and the cost of 1 pen.

Solution

Let's assume the cost of 1 pencil is x rubles and the cost of 1 pen is y rubles.

From the given information, we can form the following equations:

Equation 1: 4x + 3y = 70 (since 4 pencils and 3 pens were purchased for 70 rubles) Equation 2: 2x + y = 28 (since 2 pencils and 1 pen were purchased for 28 rubles)

To solve this system of equations, we can use the method of substitution or elimination.

Let's solve it using the method of substitution:

From Equation 2, we can express y in terms of x: y = 28 - 2x

Substituting this value of y in Equation 1, we get: 4x + 3(28 - 2x) = 70 4x + 84 - 6x = 70 -2x = -14 x = 7

Now, substituting the value of x in Equation 2, we can find the value of y: 2(7) + y = 28 14 + y = 28 y = 14

Therefore, the cost of 1 pencil is 7 rubles and the cost of 1 pen is 14 rubles.

Answer

The cost of 1 pencil is 7 rubles and the cost of 1 pen is 14 rubles.