Ok if the sticker is 5 dollars and 50 cents you need to count how many times he needs to go through the tunnel so count by 50 till you get to 550 so if the sticker was 4 dollars and 50 cents you count 50,100,150,200,250,300,350,400,450 so he would have to go through the tunnel 9 times if the sticker was 4 dollars and 50 cents
