What is the word or phrase?

You and your two friends are working in a multinational company. How can you three find out the average salary of you all without disclosing your own salary to the other two?

Count the number of triangles in the below picture?

When a clock is observed, the hour hand is at a minute mark and the minutes hand is six minutes ahead of it.

When the clock is observed again after some time, the hour hand is precisely on a different minute mark and the minute hand is seven minutes ahead of it.

Can you calculate how much time has elapsed between the two observations?

A maths symbol is hidden in the below Bar Graph. Can you decipher it?

You are in a room that has three switches and a closed door. The switches control three light bulbs on the other side of the door. Once you open the door, you may never touch the switches again. How can you definitively tell which switch is connected to each of the light bulbs?

Solve below rebus puzzle?

Accidentally, two trains are running in the opposite direction and enter a tunnel that is 200 miles long. A supersonic bird that has fled the lab and taken shelter in the tunnel starts flying from one train towards the other at a speed of 1000 mph. As soon as it reaches the second train, he starts flying back to avoid collision and meets the first train again at the other end. The bird keeps flying to and fro till the trains collide with each other.

What is the total distance that the supersonic bird has traveled till the trains collided?

What four weights can be used to balance from 1 to 30 pounds?

The following sentence is false. The preceding sentence is true.
Are these two sentences true or false?