Given that n is a whole number explain why n^2 - n is always an even number

Bradley hikes 12 miles in 3 hours. in relation to bradley’s hike, which statement describes the expression

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?

The random variable x represents the number of phone calls an author receives in a day, and it has a poisson distribution with a mean of 8.7 calls. what are the possible values of x