Yes that is a balaned equation
To solve this problem it is necessary to apply the concepts related to the condition of path difference for destructive interference between the two reflected waves from the top and bottom of a surface.
Mathematically this expression can be described under the equation

Where
n = Refractive index
t = Thickness
In terms of the wavelength the path difference of the reflected waves can be described as

Where
\lambda = Wavelenght
Equation the two equations we have that


Our values are given as
Wavelength of light



Therefore the minimum thickness of the oil for destructive interference to occur is approximately 34.0 nm
Answer:
KE + PE = KE + PE
Explanation:
In a closed system, the mechanical energy of the system is constant.
Mechanical energy is given by the sum of kinetic energy and potential energy; mathematically:
U = KE + PE
where
KE is the kinetic energy
PE is the potential energy
This means that if we consider two situations, one at the beginning and one at the end, the value of U will not change if the system is closed; this means that the sum KE + PE will remain the same, so we can write:
KE + PE = KE + PE