What is the square root of 2x equals 8

Use the normal approximation to the binomial distribution to answer this question. fifteen percent of all students at a large university are absent on mondays. if a random sample of 12 names is called on a monday, what is the probability that four students are absent?

What are the constants in this expression? -10.6+9/10+2/5m-2.4n+3m

How do you use the elimination method for this question? explain, because i really want to understand!