37. Solving a chemistry problem

224. On the radiograph between the two reference lines are 8 spectral lines of the elements. The wavelengths of the reference lines are 1260 and 1690 X, respectively. The distance between the reference marks is 70 mm. Determine the qualitative composition of the sample by measuring the distances between the first mark and the peaks of the spectral lines:
line no. 1 2 3 4 5 6 7 8
bi,mm 5.0 17.5 21.0 25.0 28.0 35.0 45.5 66.5