If you had -82 dollars in debt, then deposited 59, you would be at -23 dollars in debt. At this point, you want to be at 50 dollars positive. To do this you would need to balance the 23 dollars (by adding 23 dollars). After balancing you'd be at 0. Then deposit another 50 (so after the first deposit you'd have deposited
50+23 dollars, this equals 73 dollars). So 73 dollars is how much you need to deposit after the initial 59.