In a school, there are four subjects. Seventy percent of students study English, seventy five percent of students study Science, eighty five percent of students study Mathematics and eighty percent of students study Spanish.

Can you calculate the percentage of students that study all four subjects?

When 99 is considered higher than 100?

If 2 workers can complete painting 2 walls in exactly 2 hours.

How many workers would be needed to paint 18 walls in 6 hours?

Two in a corner, one in a room, zero in a house, but one in a shelter. What am I?

What always comes into a house through the keyhole?

With the help clues provided in the image, can you find the 5 digit key?

Two fathers and two sons decided to go to a shop and buy some sweets upon reaching. Each of them bought 1 kg of sweet. All of them returned home after some time and found out that they had 3kg of sweets with them.

They did not eat the sweets in the way, nor threw or lose anything. Then, how can this be possible?

I am not a bull but I have horns.
I am not an ass but I have a pack saddle.
Wherever I go, I leave silver behind me.

Who am I?

By removing one matchstick and adding one matchstick, can you convert the word "ZOO" to an animal name?

1 + 9 + 8 = ?
considering, 28 + 8 + 92 = 10