Question 1053531
Three persons' ages are now in the ratio 2:3:4.
After 5 years later their ages will be in the ratio 6:7:8. 
How old is the youngest person now?
<pre><b>
Then their ages at the start were 2n, 3n, and 4n for some constant n

After 5 years their ages were 2n+5, 3n+5, and 4n+5

And those ages must be 6k, 7k, and 8k, respectively, for some constant k.

2n+5 = 6k
3n+5 = 7k
4n+5 = 8k

Solving the system

{{{system(2n+5=6k,3n+5=7k)}}} gives n=1.25, k=1

{{{system(2n+5=6k,4n+5=78)}}} gives n=1.25, k=1

{{{system(3n+5=7k,4n+5=8k)}}} gives n=1.25, k=1

Their ages at the start were 2n, 3n, and 4n

That's 2(1.5) = 3, 3(1.5) = 4.5, 4(1.5) = 5

So their ages are 3, 4.5 and 5 at the start.

After 5 years their ages will be 8, 9.5, and 10.

So the youngest is ???

Edwin</pre>