Hypothesis testing with the normal distribution

when doing these types of questions,I always get the value of μ and the value of X bar mixed up, can someone please tell me how to figure out which is which

In a sense it doesnt really matter as youre calculating the difference (two tailed, so sign doesnt matter), but it would be better to say (test whether) the sample mean is a normal random variable with mean equal to the population mean and the variance equal to the population variance/n so
xbar ~ N(mu, sigma^2/n)
so here xbar = 8.95 (the mean of the sample), and the population parameters are mu=9, sigma^2=0.15^2, and n=30