I know the answer, because of calculators, but I can't quite figure out how to do it without one and I just want an explanation on how the answer was made. Please help :)

There are 40 volunteers for the research study on the Power Pill. Each subgroup of the study will contain 10 participants. Determine how many ways these participants can be selected and explain your method.

The answer correct answer is 847660528.

if x decreases by 4 then y increases by 10

step-by-step explanation:

the answer to this question is 3/19

step-by-step explanation:

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