Answer:
The answer you are looking for is x = 3/10
Explanation:
D( x )
x = 0
x = 0
x = 0
x in (-oo:0) U (0:+oo)
72/x = 3.6/0.015 // - 3.6/0.015
72/x-(3.6/0.015) = 0
72/x-240 = 0
72*x^-1 = 240 // : 72
x^-1 = 10/3
-1 < 0
1/(x^1) = 10/3 // * x^1
1 = 10/3*x^1 // : 10/3
3/10 = x^1
x = 3/10
x = 3/10