Let the constant of variation be c. We are given that y varies inversely with 2.5x, this means that: y = (c) / (2.5x) This can be written as: 2.5xy = c
Now, we a re given that y = 5.6 at x = 30. Substitute with these values in the equation to get the value of c as follows: 2.5xy = c 2.5(30)(5.6) = c c = 420
Therefore, the equation that describes the relation is: 2.5xy = 420