Răspuns:
a/b=3/7=>7a=3b
a+3b=120=>a+7a=120=>a=120:8=>a=15
7·15=3b=>b=105:3=>b=35
Explicație pas cu pas:
Răspuns:
a/b=3/7=>a=3b/7
a+b=20
3b/7+⁷⁾b=⁷⁾20
3b+7b=140
10b=140=>b=140:10=>b=14
a=3·14:7=6
_____________
a/b=3/4=>a=3b/4
2·3b/4+3b=90
6b/4+⁴⁾3b=⁴⁾90
6b+12b=360
18b=360=>b=360:18=>b=20
a=3·20:4=>a=15
