16. Solving a chemistry problem

2. To determine the wavelength λx of an unknown line in the spectrum of the analyzed sample, two lines were selected in the spectrum of iron with wavelengths λ1 = 308.375 and λ2 = 309.158 nm. Readings on the scale of the measuring microscope showed that the distance between λx and λ1 is equal to a1 = 0.25 mm, and between λ2 and λx is equal to a2 = 1.88 mm. Determine the wavelength of the unknown line.