Likelihood ratio test in R

I am in desperate need for help. I am trying to calculate the likehood ratio test in R, but I don't have allot of experience using R.

For example, to calculate the following

Suppose X1,X2,…,Xn is a random sample from a normal population with mean μ and variance 16. Find the test with the best critical region, that is, find the most powerful test, with a sample size of n=16 and a significance level α=0.05 to test the simple null hypothesis H0:μ=10 against the simple alternative hypothesis HA:μ=15.

This is the code I have up until now

#X values

sum(-dnorm(x,mean=media, sd=sdev, log=T))



print( k1/k2)

This is the very basic axample and the solution, done by hand, can be found here.

I know you also have the LRT function, but I don't know how to apply this function.

Please help, the code looks correct but it always returns 1 or 0.9999999 for any value in the parameters.

Best Regards