Răspuns:
a)x/3=y/4=k
x=3k
y=4k
3x+4y=75
3*3k+4*4k=75
9k+16k=75
25k=75
k=3
x=3*3=9
y=3*4=12
b)x/5= y/7=k
x=5k
y=7k
x+y=24
7k+5k=24
12k=24
k=2
x=5*2=10
y=7*2=14
c)x/4=y/5= z/6=k
x=4k
y=5k
z=6k
x+y+z=15
4k+5k+6k=15
15k=15
k=1
x=4
y=5
z=6
4)x/2= y/3= z/5=k
x=2k
y=3k
z=5k
2x+3y+5z=76
2*2k+3*3k+5*5k=76
4k+9k+25k=76
38k=76
k=2
x=2*2=4
y=3*2=6
z=5*2=10
Explicație pas cu pas: