+0
HOLA:

Las edades de un abuelo y de su nieto se comparan entre sí de esta manera:

1) — Los dos numeros de la edad del abuelo se suman a 11.

2) — La edad del nieto es el revés de la del abuelo.

3) — La edad del abuelo es 7 años + 2 veces de la edad del nieto.

Pregunta: Podeis precisar las respectivas edades de los dos?

[H]M
Comments  
x+y = 11

10x+y = edad abuelo

10y+x = edad nieto

10x+y = 2(10y+x)+7

Despejamos y:

x = 8

y = 3

El abuelo tiene 83 años y el nieto 38
Hola, Karmen:

Your method was very scientific, indeed! [Y] But would you believe a friend of mine who doesn’t know anything about algebra, somehow managed to give me the correct answer by just being so damned practical? According to him this was how he proceeded:

Considering what was given in the puzzle, he could see jus two possibilities, namely:

a) Abuelo’s age is 92 (that is, 9 + 2 =11). Therefore, Nieto’s age must be 29. But when 29 is multiplied by 2 and 7 is added to it, the result was 65, a far cry from Abuelo’s age of 92!

Therefore, he tried the other option, namely:

b) Abuelo’s age is 83 (8 + 3 = 11). Then, Nieto’s age must be 38. Okay, so far, so good. Now 38 * 2 = 76.

And 76 + 7 = Bingo!!...83! 'ta luego. [H]
Yeah, i knew it was 83 por el mismo razonamiento que usó tu amigo,

but to explain it, se ve muy bien con una ecuación
Hola, Karmen:

Por favor no me tomes a mal. I was not at all critizicing your algebraic approach. In fact, I highly admire your extensive knowledge of algebra. I merely wanted to point out to our foromates the fact that in many cases, number puzzles can be solved even without the use of any algebraic formulation but by simply applying a bit of practical thinking.

De todos modos, una razon por la cual me interesan tanto los number puzzles es porque además de ser divertidos, ellos tambien dan a alguien no conocedor de algebra unas ideas de cómo resolver problemas de numeros de aplicación cotidiana.

thanx for your time.

‘ta luego.[H]M