My father is four times as old as me. In 20 years, he will be only twice as old as me How is my father and how old am l?

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My father is four times as old as me. In 20 years, he will be only twice as old as me How is my father and how old am l?

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Answer 1 · 2016-11-16T18:19:42

I got that you are $10$ $10$ years old while your father is $40$ $40$ years old.

Explanation:

Let us call the age of your father $x$ $x$ and your's $y$ $y$ ; we can write:
$x = 4 y$ $x=4y$
$x + 20 = 2 (y + 20)$ $x+20=2(y+20)$

we have, substituting the first into the second:
$4 y + 20 = 2 y + 40$ $4y+20=2y+40$
$2 y = 20$ $2y=20$
$y = \frac{20}{2} = 10$ $y=20/2=10$
so that:
$x = 4 \cdot 10 = 40$ $x=4*10=40$

Answer 2 · 2016-11-16T18:21:41

I am currently 10 years old and my father is currently 40 years old.

Explanation:

Let's let my age be $m$ $m$ .

So right now my father's age, Let's call it $n$ $n$ is $4 m$ $4m$ or

$n = 4 m$ $n = 4m$ .

So in 20 years I will be $m + 20$ $m + 20$ years old and my father will be $n + 20$ $n + 20$ years old. But at this time he will be only twice as old as me. So we can right an equation for our age in 20 years as:

$n + 20 = 2 (m + 20)$ $n + 20 = 2(m + 20)$

Substituting $4 m$ $4m$ from the first equation for $n$ $n$ in the second equation and solving for $m$ $m$ while keeping the equation balanced gives:

$4 m + 20 = 2 (m + 20$ $4m + 20 = 2(m + 20$

$4 m + 20 = 2 m + 40$ $4m + 20 = 2m + 40$

$4 m + 20 - 2 m - 20 = 2 m + 40 - 2 m - 20$ $4m + 20 - 2m - 20 = 2m + 40 - 2m - 20$

$2 m = 20$ $2m = 20$

$\frac{2 m}{2} = \frac{20}{2}$ $(2m)/2 = 20/2$

$m = 10$ $m = 10$

So my age is currently 10 years old.

Substituting 10 for $m$ $m$ is the first equation gives:

$n = 4 \cdot 10$ $n = 4 * 10$

$n = 40$ $n = 40$

Answer 3 · 2016-11-16T18:44:26

I am 10 years old now and and my father is 40.

Explanation:

Although we are dealing with the ages of two people, we only need to use one variable, because we know how their ages are connected.

Let my present age be $x,$ $x," "$ then my father's age is $4 x$ $4x$

In 20 years time
My age will be $x + 20$ $x+20$ and my father's age will be $4 x + 20$ $4x +20$

Then, twice my age will be the same as my father's age.

"2 x younger age = older age"
Do not make the mistake of doubling the father's age!

$2 \times (x + 20) = 4 x + 20$ $2xx(x+20) = 4x+20$

$2 x + 40 = 4 x + 20$ $2x+40 = 4x +20$

$40 - 20 = 4 x - 2 x \leftarrow$ $40-20 = 4x-2x" "larr$ keeping x positive

$20 = 2 x$ $20 = 2x$

$10 = x$ $10= x$

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My father is four times as old as me. In 20 years, he will be only twice as old as me How is my father and how old am l?

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