Bob climbs a mountain, but starts below sea level. he climbs the same number of feet each hour. if the function showing his elevation for any hour is y = 850x – 325, what elevation, in feet, did he start at?
a.
325
b.
850
c.
–850
d.
–325

If x is representing the number of hours he has been climbing, and y represents the total number of feet, then the answer is D: -325. It is stated in the question that he started below sea level, so the answer cannot be A or B, as they are both above sea level. Then, to see at what elevation he started, plug x+0 into the equation. 850x will become 0, and y=-325.

answer: Associative Property of Addition (Numbers)