660:99

To simplify the given expression, we can divide both the numerator and denominator by their greatest common divisor (GCD), which in this case is 33.

So, 660/99 simplifies to (660 ÷ 33) / (99 ÷ 33).

Calculation: 660 ÷ 33 = 20 99 ÷ 33 = 3

Therefore, 660/99 simplifies to 20/3.