Find the ratio between total number of Labors working in 2012 and 2013 together to total number of labors working in 2015 and 2016 together?

Required Ratio =

$frac{{left( {120 + 180} ight) + left( {240 + 120} ight)}}{{left( {300 + 360} ight) + left( {360 + 300} ight)}}$

$= frac{{300 + 360}}{{660 + 660}} = frac{{660}}{{1320}} = frac{1}{2}$