6. Solving a chemistry problem

9(3). Cis-1,2-dichloroethylene in vinylidene chloride was determined by gas chromatography using toluene as an internal standard, and the following data was obtained for the calibration curve:
Sx/St 0.72 0.90 1.08 1.28
w,% 0.5 1 1.5 2

Calculate the mass fraction (%) of cis-1,2-dichloroethylene in the test sample from the following data on the peaks of the analyte and standard substance (take k=1)
Cis-1,2-dichloroethylene peak Toluene peak
Base Height Base Height
12 60 15 50