Răspuns:
[tex]\dfrac{a}{4} =\dfrac{b}{5} ,~~\dfrac{a}{b} =\dfrac{4}{5},~~~\dfrac{a+b}{b} =\dfrac{4+5}{5},~~~\dfrac{27}{b} =\dfrac{9}{5},~deci~~b=\dfrac{27*5}{9} =15[/tex]
Inlocuim in a+b=27, ⇒a+15=27, ⇒a=27-15=12
Deci a=12, b=15.
Explicație pas cu pas:
am aplicat proporții derivate...