How do I solve for this normal distribution variable mathematically and in R?

Question

This is the question I have attempted to answer but unsure about my solution:

If $X$ is $N(650,625)$, find a constant $c>0$ such that $P(|X−650|≤c)=0.9544.$

My Proposed Solution

The expected answer is $c=50$ but I have tried with different combinations of qnorm() including qnorm(0.9772) and qnorm(0.9772, 650,25) and I am not arriving at this outcome.