Algebra is amazing - Where is the father?

[Juz]

A mother is 21 years older than her son.

In 6 years, the mother will be 5 times older than her son.


Question: Where is the father.


This can be solved with algebra!















































Solution:


Mothers age = X
Sons age = Y


X = (Y + 21)
X + 6 = 5 (Y + 6)

(Replace X with Y + 21 above)

(Y + 21) + 6 = 5Y + 30
Y + 27 = 5Y + 30

(Subtract 30 from each side)

Y – 3 = 5Y

(Subtract Y from each side)

-3 = 4Y

(Divide each side by 4)

Y = sons age = -3/4


So if the son is –3/4, then the son is –9 months old





































Where is the father? – Clearly he is inside the mother!


Juz

[Alex85]

Thats brilliant will have to use that one on my mathematics lecture at uni, i'm sure he'll enjoy it!!!

[dry suit diver]

Hmmm technically how do they know its a son so soon.


but apart from that brilliant

[Juz]

Originally Posted by dry suit diver

Hmmm technically how do they know its a son so soon.


but apart from that brilliant

When you pass it on, please fell free to chnage it to child.

Juz

[Sooty Stoo]

I would guess that it's a daughter rather than a son.

If there is a lot of stress then you're more likely to have a daughter than a son, and all these people watching the bloke whilst he's 'on the job' will put him under stress, methinks

EDIT-just checked, there's 147 people looked at this bloke

[Marky Mark]

And presumably the mother is on the hippopotamus skin

[nickb]

Bit of a convoluted way of doing the simultaneous equations.

No need to add the six 'cos in six year's time she'll still be 21 years older, so:
X = Y + 21
X = 5Y or X = Y + 4Y
therefore:
4Y = 21, so Y = 21/4 = 5.25
now subtract the 6 and the child is -3/4

Which avoids having to multiply out the factor at the beginning.

[ratcliffe]

I didn't use algebra to solve this, I used applied modern thinking.

The father will be down the DHSS office claiming his handouts...

[chas49]

Originally Posted by Juz

So if the son is –3/4, then the son is –9 months old

Originally Posted by Juz

.....

Where is the father? – Clearly he is inside the mother!

Originally Posted by ratcliffe

I didn't use algebra to solve this, I used applied modern thinking.

The father will be down the DHSS office claiming his handouts...

At least everyone else in the queue will have something to watch

(Oh - and it stopped being the DHSS quite a long time ago Derek, do keep up! )