If you want a sequence that subtracts 6 each time, then we'd have to have a nth term.
125, 119, 113 etc will be your pattern
Since we are subtracting 6 each time, the nth term will start with -6n
Then we see what that equation looks like: -6 as the first term, -12 as the second etc.
So we have to add a certain amount so the sequence starts at 125, which is to plus 131 to get to 125.
So now the pattern starts at 125 and decreases by 6 each term.
So U_n = -6n + 131
