The depth of a lake, d, varies directly with r, the amount of rainfall last month. if k is the constant of variation, write an equation to represent the situation.

d = kr

Explanation:
We know that the depth (d) varies directly with the amount of rain (r).
This means that as the amount of rain increases, the depth increases and vice-versa.
The depth would depend on r multiplied by a constant of variation (k)

Translating this into equation, we would get the following:
d = kr

Hope this helps :)