There is a way to avoid the ":" stuff. Consider the fraction:
We need to remove the fraction in the denominator of the "overall" fraction. How would you do this? Well, note that if we multiply by 5 the result is an integer: 2. But what we multiply in the denominator we must also multiply in the numerator. So:
(No offense Krizalid. I hate ratio notation with a passion. )
-Dan