What has one letter and starts with an E?

When my father was 31 I was 8. Now he is twice as old as me. How old am I?

I know there are two methods by using three time the same number with a plus(+) operator , you can make sum as 60.

One of them is 20+20+20.

whats the other way ?

What is more useful when it is broken?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

I am a type of food that is often found in the fridge and can be white in colour. What I am?
Hint 1: I am a dairy product.
Hint 2: You can spread me on the bread.

There are five vowels (a, e, i, o, u) in the English language.
Can you tell us a word that contains all these vowels?

Twenty frogs are sitting on a log floating on the surface of a river. Two of them decide to jump off into the water.

How many frogs are there on the log at this moment?

The more you take me, the more you leave me behind.
Who Am I?

What is the Surname of Barbie Doll?