Răspuns :
a+b+c=122
a=75% din b= 75/100*b= 3/4 *b= 3b/4
b=30% din c=30/100* c= 3/10*c= 3c/10
a=(3*3c/10)/4= 9c/10/4= 9c/10* 1/4= 9c/40
9c/40+4c/10+c=122 aducem la acelasi numitor
9c+16c+40c=4880
65c=4880
c=4880/65= 976/13
a=9* 976/13/40=8784/13/40= 8784/13 *1/40= 2196/13 *1/10= 1098/13 *1/5= 1098/65
b=3*976/13/40= 2928/13 *40= 366/13 *1/5= 366/65
a=75% din b= 75/100*b= 3/4 *b= 3b/4
b=30% din c=30/100* c= 3/10*c= 3c/10
a=(3*3c/10)/4= 9c/10/4= 9c/10* 1/4= 9c/40
9c/40+4c/10+c=122 aducem la acelasi numitor
9c+16c+40c=4880
65c=4880
c=4880/65= 976/13
a=9* 976/13/40=8784/13/40= 8784/13 *1/40= 2196/13 *1/10= 1098/13 *1/5= 1098/65
b=3*976/13/40= 2928/13 *40= 366/13 *1/5= 366/65
x+y+z=122
x=75/100*y=3/4 * y
y=30/100*z ⇒ z=10y/3
inlocuiesc in prima
⇒3y/4+y+10y/3=122
aduc la acelasi numitor
9y+12y+40y=122*12
61 y=122*12⇒ y=12*122/61=24⇒ x=3*24/4=18 ⇒ z=10*24/3=80
verificare x+y+z=18+24+80=122
x=75/100*y=3/4 * y
y=30/100*z ⇒ z=10y/3
inlocuiesc in prima
⇒3y/4+y+10y/3=122
aduc la acelasi numitor
9y+12y+40y=122*12
61 y=122*12⇒ y=12*122/61=24⇒ x=3*24/4=18 ⇒ z=10*24/3=80
verificare x+y+z=18+24+80=122