Problema 2: Julián le dice a su hermano Pepe: "hace cuatro años yo era cuatro veces más viejo que tú, pero dentro de cinco años solamente te doblaré la edad". Calcula la edad actual de cada uno

JuIian: 22 years

Pepe: 8.5 years

Step-by-step explanation:

(English question: JuIian says to his brother Pepe: "four years ago I was four times older than you, but in five years I will only double your age". Calculate the current age of each)

Let's call JuIian's age by X, and Pepe's age by Y.

Four years ago, JuIian's age was four times Pepe's age, so:

(X-4) = 4 * (Y-4)

After five years, JuIian's age will be the double of Pepe's age, so:

(X+5) = 2 * (Y+5)

Now, rewriting the equations, we have:

X - 4 = 4Y - 16 - > X = 4Y - 12

X + 5 = 2Y + 10 - > X = 2Y + 5

Comparing the two results of X, we have:

4Y - 12 = 2Y + 5

2Y = 17

Y = 8.5 years

Now, calculating the value of X:

X = 2Y + 5 = 17 + 5 = 22 years