1) a/b=3/7⇒7a=3b=k⇒a=k/7,b=k/3⇒2a+5b=2k/7+5k/3(numitor comun 21)=18k/21=62⇒18k=1302⇒k=72,(3)⇒a=10,(3);b=24,(1). 2)2x/5y=3/8⇒16x=15y=k⇒x=k/16,y=k/15⇒x+y=k/16+k/15=93(numitor comun240) =31k/240=93⇒k=22320/31=720⇒x=45,y=48. P: 45+48=93 3.a) aici vom folosi "regula de trei simpla". 20 m(muncitori)............15 zile
15m(muncitori).............x , 20/15=15/x⇒15x15/20=225/20=11,25 zile b)20/10=15/x⇒x=7.5 zile. Sper ca te-am ajutat!