Our product and our sum always give the same answer. Who are we?

I always drive my customer away.

Who am I?

Can you solve the maths in the below-given picture equation?

How many triangles are there on the puzzle below?

If,
29 - 1 = 30
9 - 1 = 10
14 - 1 = 15

Based on similar logic, Can you prove that the below algebraic equation is true?
11 - 1 = 10 ?

An American nightclub called 'The Coconut Grove' had a terrible fire in which over 400 people died. A simple design flaw in the building led to a high death toll. Subsequently, regulations were changed to ensure that all public buildings throughout the country eliminated this one detail, which proved deadly. What was it?

When we see 2 but call 10?

When you stop to look, you can always see me. But if you try to touch me, you can never feel me. Although you walk towards me, I remain the same distance from you. What am I?

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

What is the largest amount of money that you can possess in change and still if someone asks you for a dollar, you won't be able to give?