1.
Slope formula:
m = Difference between y points/difference between x points
points x, y = (60,900) , (15,450)
m = (900-450)/ (60-15) = 450/45 =10
The calculation was correct.
2.
Apply the slope formula for 2 points from the table.
(x,y) = (0,300)
(x,y)= (30,600)
m = (600-300)/ (30-0) = 300/30 = 10
We obtained the value of the slope. Confirm.
3. The slope tells the ratio of elevation change between two points on time.
Total elevation change: Final point - initial point
initial point: 300 ft
Final point: 300 ft
Elevation change : 300-300 = 0