book Maths Puzzle Numerical Ability

The ages of Old and Young total 48. Old is twice as old as Young was
when Old was half as old as Young will be when Young is three times as
old as Old was when Old was three times as old as Young.
How old is Old?

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book Other Question

I need to graph the equation y^3+x^2=8. I got as far as y^3=8-x^2, but I don't know what to do further. I don't know what expression I enter for y o obtain the correct graph. An infinite geometric series has 1 and 1/5 as its first two terms: 1,1/5,1/25,1/125,..... What is the sum, S, of the infinite series?
a)1/25
b)1/4
c)1
d)5/4