a=norma muncitor 1
b=norma muncitor 2
120%a+115%b=1995
90%a+110%b=1710
120a+115b=199500
9a+11b=17100
24a+23b=39900
9a+11b=17100 b=(17100-9a)/11
24a+23×(17100-9a)/11=39900
264a+393300-207a=438900
57a=45600
a=800 piese muncitor 1
b=(17100-9×800)/11=900 piese muncitor 2