Assuming that it is American roulette, The number 19 appears once out of 38 other numbers. that means you have a 1/38 probability of winning.
that 1/38 chance will pay you $35 and the 37 other ties will pay you $-1. So let's say you play only 38 times. Probability says you will lose 37 times and win once, meaning you will lose $37 and win $35. All in all you lose $2 every 38 tries. How many
groups of 38 tries is there in 1600? 42.105. Multiply that by -2 and you get 84.21, which is close enough to 84.36 with the error being a difference of rounding.