Any linear equation can be written as
y = mx+b
where m is the slope and b is the y intercept
m = 1/2 in this case. It represents the idea that the snow fell at a rate of 1/2 inch per hour. In other words, the snow level went up 1/2 an inch each time an hour passed by.
b = 8 is the y intercept. It's the starting amount of snow. We start off with 8 inches of snow already.
The info "snow fell for 9 hours" doesn't appear to be relevant here.
