While setting up a game of bowling, someone decided to increase the same, but non-standard, number of pins in each successive row. We know they placed 4 pins in the first row, 12 pins in the last row, and used in total 40 pins. However we cannot see from the end of the alley how many rows were placed, nor many pins were added between rows. Determine those two quantities.

Please give only typed answer otherwise i will Downvote