What does this rebus means ?

PROG WORKRESS

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

I am a type of vehicle that has two wheels and is powered by humans. What am I?
Hint 1: You can ride me for exercise.
Hint 2: I am environment-friendly.

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?

You see a mathematical expression in the picture. Can you think of a movie that this expression refers to?

What does this below rebus puzzle mean?

How many bricks does it take to complete a building that is 15 feet wide, 30 feet deep, and 12 feet tall made of brick?

Spot 5 differences in two Christmas tree below:

Solve The below Equation:

ALFA + BETA + GAMA = DELTA

Suppose you are sitting in an interview and the interviewee asks you an aptitude question.

You have three buckets with a capacity of 4 litres, 8 litres and 10 litres and you have a large tank of water. Now you have to measure 3 litres of water precisely using those buckets. How will you do it?