There are 11 counters in a bag. 6 of these counters are green.
5 of these counters are red.
Some more red counters are put into the bag.
A counter is then taken at random from the bag.
The probability that the counter is red is
3
How many red counters were put into the bag?

not only in mathematics, scientific proof also are required in the other field of science. also maths proofs are of particular structure, containing steps and logics. so proving is like doing science, it is science. that's why it is important to prove. 

an inaccurate proof leads to errors, or stating results that are not accurate.  which wil mess the probelm up you dont want this

(x) - (y) = (1 + 4i)

i dont know what you want me to answer for this but im guessing 2: 11?