Răspuns :
11.
x/5=20/12
12x=5*20
12x=100 |:12
x=8,(3)
12.
2n+4=3n-15 |+15
2n+19=3n |-2n
19=n
x/5=20/12
12x=5*20
12x=100 |:12
x=8,(3)
12.
2n+4=3n-15 |+15
2n+19=3n |-2n
19=n