Răspuns:
Explicație pas cu 1
1.
a/b=2/3 (2a/b+5)/(-2a/b+3)=(2·2/3+5)/(-2·2/3+3)=(4+15)/(-4+9)=19/5
2.
a)6/x=4/2=2 x=6:2=3
b)5/5x=15/18 1/x=5/6 x=6/5
3.
a=3b/5
2a+5b=93 2·3b/5+5b=93 6b+25b=93·5 31b=93·5
b=3·5=15 a=3·15/5=9
4.
a/9=5/b ⇒ab=9·4=45 ab-5=45-5=50
5.
8 caiete...............................16 lei
6 caiete.................................x=6·16/8=6·2=12 lei
6.
x/4=y/6=z/9=(x+y+z)/(4+6+9)=1520/19=80
x=4·80=320 lei
y=480 lei
z=720 lei
