1) 8r.......................5ore
10r.....................x ore
......................................marimile fiind invers proportionale avem :
8·5=10·x⇔x=8·5/10=4 ore
2)a+b+c=75
a/3=b/5=c/7=k⇒a=3k,b=5k,c=7k si inlocuind in suma aven :
3k+5k+7k=75⇔15k=75⇔k=5
a=15,b=25,c=35
Analog se rezolva 3) si 4) doar ca ai alte relatii intre a,b si c.
3)x·2=y·3=z·6=k si inlocuiesti in relatia intre a, b si c.
4) a+b+c=122 (1)
a=75/100·b=3/4·b=3/4·3/10·c=9/40·c
b=30/100·c=3/10·c
si inlocuim in relatia (1) de unde aflam pe c.
