Light is incident from above on two plates of glass, separated on both ends by small wires

Question:

Light is incident from above on two plates of glass, separated on both ends by small wires of diameter d = 0.600 mm. Considering only interference between light reflected from the bottom surface of the upper plate and light reflected from the upper surface of the lower plate, state whether the following wavelengths give constructive or destructive interference:

(a) λ = 600.0 nm;

(b) λ = 800.0 nm;