a.
yes, the candle starts high/tall, then as it melts over time it gets smaller and smaller until is all gone.
b.
y = mx + b
y = 4/2x + 8
y= 2x + 8
c.
Well, since it's slope/unit rate is greater/faster it will burn quicker, therefore you will still start at 8 on the y ais, but it would decrease 3 in. each hour, instead of 2, like the orignal problem.