When you want to find the value of a variable, isolate it.
First, add 355 to both sides of the equation to get rid of the -355 on the left side of the equation. We get -n = -602.
We're not done yet! We need to change the -n to +n, or just n. Multiply both sides by -1. We get n = 602.
n = 602.
Hope that helped you.