3/4 * 1 1/4 * 7 1/2 * 2 1/4 : 7 1/2

Convert mixed numbers to improper fractions: 3/4 * 5/4 * 15/2 * 9/4 : 15/2. Perform multiplication: (3*5*15*9)/(4*4*2*4) = 2025/128. Perform division: (2025/128) / (15/2) = (2025/128) * (2/15) = 2700/1920. Simplify the fraction: 2700/1920 = 270/192 = 135/96 = 45/32. The final answer is 45/32.