Need help

Im trying to figure out the hypothesis testing for normal dist and Norm.S inv. I made up a scenario and im not sure if my response to my scenario is corect in regards to the normal dist and norm.s. and p value and z. . im extremely confused .

For my scenario i said a shop has average daily selling of $ 75. shopkeeper claims that average daily selling of shop has greater than its average of $ 75.to support this claim, he collects a sample of 25 days and finds that average daily selling is $80. The population standard deviation is known $9.use significance level of 5%

H₀ : u=75

H₁ : u>75

=(75-80)*9/9^0.5

=-15

Nom.dist(75,80,9/9^.5.)

=Norm.s.inv(A)

Using the z to p value calculator with a=.05, 1 tailed test and z=-15, you get

P-value =0.0027 {from Ztable}