Question

in doua clasoare sunt 270 timbre. daca mutam 10% din timbrele din primul clasor in cel de-al doilea clasor, cele doua clasoare vor avea acelasi numar de timbre. cate timbre se afla in fiecare clasor?

Answer 1

a+b=270⇒a=270-b
a-10/100*a=b+10/100*a
a-a/10=b+a/10
9a/10=b+a/10
9a=10b+a
8a=10b
8(270-b)=10b
2160-8b=10b
2160=18b⇒b=120 timbre (in al doilea clasor)
a=270-b
a=150 timbre(primul clasor)