If n-8=-3, what is 3n?

Can someone answer it, and plot it, for 20 points and brainliest answer? p. s. they're the same ! : )

Janet drove 300 miles in 4.5 hours. write an equation to find the rate at which she was traveling

James adds two numbers a + b. sally adds the same two numbers but reverse the order b + a what property of addition assures us that james and sally will get the same sum