Question

Determina 3 nr nat,stiind ca suma lor este 122 si primul reprezinta 75% din al doilea iar al doilea30% din al treilea

Answer 1

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

Answer 2

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