These are treated the same as simply balancing equation unless you either have to divide or multiply both sides by a negative number to solve for n. Each time you multiply/divide by a negative the direction of the sign will change. (i.e if you have a > and you must divide by -2 then the sign will flip form > to <; this step is repeated every time you must multiply/divide by a negative)
1) 3<-5n+2n (restate question)
2) 3<-3n (combine like terms)
3) 3/-3<-3n/-3 (this is where the dividing by a negative comes into play. Notice how the answer in step 4) is now using a greater than sign rather than a less than sign)
4) -1>n (There is the final answer. Remember about the flipping of the greater than sign when dividing/multiplying by a negative.)
The answer -1>n would usually be written as n<-1 however either are acceptable because they are the same. (just written differently)