My 8 year old came to me for with his maths homework but i had never come across this method. at his age i used the bus stop method but i have no idea what this is can someone explain this layout?

Jamie went to home depot.she bought 25 bags of soil that cost $9 per bag.she bought 15 pots at $8 each, and she bought 23 bags of pebbles at $15 each.she used a coupon that gave her $5 off for every 100 dollars she spent. how much did jamie pay at the end?