1. The problem asks to find \textit{three quarters} of 1200. 2. To express \textit{three quarters} mathematically, we use the fraction $\frac{3}{4}$. 3. The formula to find a fraction of a number is: $$\text{Fraction of a number} = \text{Fraction} \times \text{Number}$$ 4. Substitute the values: $$\frac{3}{4} \times 1200$$ 5. Multiply numerator and denominator: $$= \frac{3 \times 1200}{4}$$ 6. Simplify the fraction by dividing numerator and denominator by 4: $$= \frac{\cancel{3} \times 1200}{\cancel{4}} = 3 \times 300$$ 7. Calculate the multiplication: $$= 900$$ Therefore, three quarters of 1200 is \textbf{900}.