Răspuns:
Explicație pas cu pas:
4
x/7=y/5=z/11=(x+y+z)/((7+5+11)=138/23=6
x=6·7=42
y=6·5=30
z=6·11=66
5
0,5/3=4/24=(0,5+4)/(3+24)=4,5/27=(4-0,5)/(24-3)=3,5/21
1/6=4/24 1/4=6/24=12/48
6
15·280/100=15·28/10=3·28/2=3·14=42
7
6%lsmantana 100% l lapte
x 15l lapte
x=6·15/100=0,9l