Answer:
La calculadora y el cuaderno costaba 9 y 1,8 euros hace tres días.
Step-by-step explanation:
A partir del enunciado podemos construir el sistema de ecuaciones lineales:
Hace tres días:
(1)
Actualmente:
(2)
Donde:
- Precio de la calculadora.
- Precio del cuaderno.
Por métodos algebraicos, tenemos que el sistema de ecuaciones tiene la siguiente solución:
, 
La calculadora y el cuaderno costaba 9 y 1,8 euros hace tres días.
Answer:
Givens
- The cost of the square windows is 3 euros per meter, and 12 euros for the crystal.
<h3>If a window has 2 meters side, how much would it cost? (A)</h3>
Notice that the window is a square, that means all four sides are congruent, so it has 8 meters in total, which would cost 24 euros plus the crystal. Therefore, the total cost of a window with 2 meters side is 24+12 = 36 euros.
Specifically, the function of the cost is:
, where
represents meters of sides. (C)
<h3>If we paid 60 euros, the dimensions are (B)</h3>

The window has 16 meters between the four sides, which gives 5 meters per side.
The graph of the function is attached.