Need help with 9 I don’t get it

What's the difference between: x≥0 and nonnegative integer. ?

What is the result of converting 60 ounces to pounds remember there are 16 ounces in a pound

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 jame pay at the end?