Math , help plss thnx

What is the measure of angle afe? 79 81 91 99

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?

2x minus y equals 6, x plus y equals negative 3