|x+3/4|= 5 6/7 please help with this question from 6.2 russian mathemetics school

Factor the monomial completely 42a3b3

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?

This is about circle theorems. someone asap : (