Răspuns:
a) x/2=y/5⇒5x=2y
3x+4y=52⇒3x+10x=52
13x=52
x=4
4/2=y/5⇒y=4x5:2=10
b) x/4=y/9⇒9x=4y
5x-y=88 /x4
20x-4y=352
20x-9x=352
11x=352
x=32
32/4=y/5⇒y=32x9:4=288:4=72
c) x/2=y/3=z/4⇒3x=2y 4y=3z
x+y+z=18 /x3
3x+3y+3z=54
2y+3y+4y=54
9y=54
y=6
x/2=6/3⇒x=6x2:3=4
6/3=z/4⇒z=6x4:3=8
d)x/3=y/4/=z/5⇒4x=3y 5y=4z
x+2y+3z=104 /x4
4x+8y+12z=416
3y+8y+15y=416
26y=416
y=16
x/3=16/4⇒x=16x3:4=12
16/4=z/5⇒z=16x5:4=20
Explicație pas cu pas: