Plz ned help

Add the two expressions 3.8b - 7 and 2.9b + 9 enter your answer in simplified form

Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.1. (round your answers to four decimal places.) (a) if the distribution is normal, what is the probability that the sample mean hardness for a random sample of 8 pins is at least 51?

Which of the following equations is equivalent to x/3-6/x=1