Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

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

You can take four of the five letters out of this word, but the pronunciation never changes. What is the word?

Using four sevens (7) and a one (1) create the number 100. Except for the five numerals, you can use the usual mathematical operations (+, -, x, :), root and brackets ()

Prove that the below maths equation is true.

8 + 8 = 91

As you can see that fifteen matches have been used to form an arrangement. What you have to do is remove any six of them to make them ten.

John was working on a Chemical Mixture whose weight comprise 90% liquid and 10% solid. The total weight of the mixture is 20 pounds. After a while, John noticed that some of the liquid evaporated and now the liquid comprises just 50% of the weight.

What is the weight of the chemical mixture now?

Replace the (?) with the correct mathematical signs to make the expression equal to 59.

18 ? 12 ? 4 ? 5 = 59

I have an eye but still cannot see.

Who am I?

In the given figure, move three matchsticks so that the resulting figure contains two rectangles.