Propositiones ad Acuendos Juvenes/Problems/2 - De Viro Ambulante in Via

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Propositiones ad Acuendos Juvenes by Alcuin of York: Problem $2$

De Viro Ambulante in Via
A Walker
A man walking down the road saw others coming towards him, and he said to them,
"I wish there were others with you, as many as you are,
plus a quarter of the sum that would be,
plus half of that last amount.
Then with me there would be $100$ altogether."
How many did he see on the road?


Solution

$36$.


Proof

Let $x$ be the number seen on the road.

Then we have:

$x + x + \dfrac {x + x} 4 + \dfrac 1 2 \paren {\dfrac {x + x} 4} + 1 = 100$

That is, after algebra:

$\dfrac {11 x} 4 = 99$

Hence the result.

$\blacksquare$


Sources