To simplify the expression 12mũ5:144mũ2, we can divide the coefficients and subtract the exponents.

12mũ5 ÷ 144mũ2 = (12/144) * (m^(5-2)) * (u^(1-1))

Simplifying the coefficient gives us 1/12.

The variable m has an exponent of 5-2 = 3.

The variable u has an exponent of 1-1 = 0, which means it cancels out.

Therefore, the simplified expression is (1/12) * m^3.