To get equivalent ratio for the above expression you multiply or divide both the numerator and the denominator by the same number. So, infinite number of ratio is equivalent to the above expression.
1> (27/3) : (15/3) = 9 : 5
2> (27 *2) : (15*2) = 54 : 30
3> (27*10) : (15*10) = 270 : 150