Question

A sand dune stands 5 feet above sea level. The hill is eroding at a rate of 1 foot per 20 years. Let y represent the height of the sand dune after x years. Which equation represents the situation?

Answer 1

y at initial time is 5 and therefore 5 is a constant
x is the amount of years so it is one foot per 20 years therefore (1/20) x or (x/20)

The height of the sand dune at any time is 5 foot - (x/20)
therefore 
y= 5-(x/20)

Answer 2

Answer:

y = -1/20x + 5

Step-by-step explanation:

A sand dune stands 5 feet above sea level. The hill is eroding at a rate of 1 foot per 20 years. Let y represent the height of the sand dune after x years. Which equation represents the situation?

slope: $-\frac{1}{20} x$ (this is because the hill is eroding)

Initial value: 5

Hope this helped :)