Just comparing your (x, y) points to the values on the table, it looks like b) would be the quick answer. Since it states under the table to use average values within each range.
So for x=62 (the weight), we have y=122 (the iron count) which would be the average of the range between 115 and 129.
Similiarly, x=70 corresponds to y=146, which is the average of 139 and 153.
You could take the average values of your highest and lowest iron count ranges compare them to the max-min weight to get your slope. Looks like it would be (155-112)/(73-58)= 43/15= 2.8666 repeating. That would make sense with the slope in the equation listed in b) as well.
<span>
</span>
