You solve it basically like any other equation, isolating numbers etc. By this, I mean you will do the inverse of whichever operation is being used. For example if 5<u-3 Then you would add 3 to both sides to get 8<u. However there is a slight catch, whenever you multiply or divide by a negative number, you must switch the direction of the sign. For example 6<-3u. To solve this you have to divide by -3 on both sides, so you 'flip' the sign to get -2>u.
Hope this helped!