Algebra-2

We can set up the equation as follows:

Intensity = k * (1 / (d * r²))

Using the given values, we can solve for the constant of proportionality, k:

10 = k * (1 / (4 * 3²))
10 = k * (1 / (4 * 9))
10 = k * (1 / 36)
k = 10 * 36
k = 360

...