daca 6/9=3/7, aflati cat la suta reprezinta a din a+b

Răspuns :

a+b=10k
a/b=3/7 
a=3k
b=7k
a+b=10k
x% din 10k=3k
x/100x10k=3k/:10k
x/100=3/10
x=30%