Explicație pas cu pas:
2. 2x+y/3y-x=1 2x+y=3y-x 3x=2y x/y=2/3
4.x+y+z=120
x/5=y/12=z/13 x=5y/12, y=12z/13, x=5z/13
5z/13+12z/13+z=120
5z+12z+13z=1560
30z=1560
z=52
x=5×52/13=20
y=12×52/13=48
5.a)13m.........117lei
52m...........x
x=52×117/13
x=468lei