LCM( 25, 55 ) = 275
The formula for finding LCM is
$$ \text{LCM} (a, b) = \frac{ a \cdot b }{ \text{GCD}(a,b)} $$In this example we have: a = 25, b = 55 and GCD(25, 55) = 5.
$$ \text{LCM} (25, 55) = \frac{ 25 \cdot 55 }{ \text{GCD}(25,55)} = \frac{ 1375 }{ 5 } = 275 $$