If 21x = 79x, what is the value of x?

A chicken farmer has figured out that a hen and a half can lay an egg and a half in a day and a half. How many hens does the farmer need to produce one dozen eggs in six days?

A 52% bias toss for head using the 51% tail bias coin was done to obtain a fair result.

Can you find how bias is the floor in this case?

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?

Below, you will find the mathematical proof that 10 equals 9.99999?. But is that possible or there is something wrong about it? Can you find the error?

x = 9.999999...
10x = 99.999999...
10x - x = 90
9x = 90
x = 10

You are given a cube that is made with the help of 10x10x10 smaller cubes summing up to a total of 1000 smaller cubes. You are asked to take off one layer of the cubes.
How many remain now?

Can you arrange four 9's and use at most 2 math symbols, to make the total 100?

Solve below popular number sequence
314 159 265 358 979 323 846 ?

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?