1. If the current age is x, then age n years ago = x−n. If the current age is x, then age n years later = x+n. If the current age is x, then age n years ago = x – n. The ages in a ratio a : b will be ax and bx.

2. 

1. If the present age is x, then n times the age is nx.
2. If the present age is x, then age n years later/hence = x + n.
3. If the present age is x, then age n years ago = x – n.
4. The ages in a ratio a : b will be ax and bx.
5. If the present age is x, then 1/n  of age is x/n 

3. If the age is given in the form of a ratio, for example, p:q, then the age shall be considered as qx and px. If you are assuming the current age to be x, then n times the current age will be (x×n) years. If you are assuming the current age to be x, then 1/n of the age shall be equal to (x/n) years.