Răspuns :
15 muncitori..........................30 zile
30 muncitori...........................x zile
i.p.=>15x30/30=15 zile
15 muncitori -------30 zile
30 muncitori -------x zile
x = 15 ×30 : 30
x = 450 : 30
x = 15 zile
30 muncitori -------x zile
x = 15 ×30 : 30
x = 450 : 30
x = 15 zile