It would help so much if you were to type out the table in table format. What does "1234" stand for, and where do you find it in the table? I urge you to copy the original problem here, all of it. Or, could you take a photo or screen shot of the original problem and then share the illustration here?
Is this what you meant? Probably yes, but I wish I didn't have to guess.
Rooms
cleaned Cost
1 $125
2 $175
3 $225
4 $275
You can see for yourself that the increase from $125 to $175 is $50. From $175 to $225 the increase is the same ($50). And so on.
So, after the first room has been cleaned, the cost of having additional rooms cleaned is $50 per room.
Just to get the cleaner to your house apparently costs $75.
Then $75 + 1($50) = $125 for one room.