If eleven plus two equals one, what does nine plus five equal?

Considering the below equation:

V + II - VI = 10
IV - X + VIII = 20
IV - VII + VI = 30

Then, I + II + III = ?

If you drop me I’m sure to crack, but give me a smile and I’ll always smile back. What am I?

I have eight fingers and two thumbs but I do not live. What Am I?

If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

A network of 20 x 10 squares is given to you.

Can you calculate how many unique squares and rectangles can be formed combining two or more individual squares ?

In the Thar desert, 3 men found a big 24L Jar is full of water. Since there is a shortage of water so they decided to distribute the water among themselves such that they all have equal amounts of it. But they only have a 13L, a 5L and an 11-litre Jar.

How do they do it?

What word is pronounced the same if you take away four of its five letters?

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

There were three women in all the swimming costumes!
One was happy and the other two were sad!
The happy one was crying and the sad ones were smiling.
Why was this?