Well, when multiplying fractions together, you don’t really have any problem of converting fractions for common denominators or any of that stuff and instead it’s actually quite simple because you just have to straight multiply the numerators and the denominators
9/2 * 20/3 * 9/4
= (9 * 20 * 9)/(2 * 3 * 4)
= (1620)/(24)
= 1620/24
= 67.5
So, in conclusion, 9/2 * 20/3 * 9/4 is equal to 67.50 or 1620/24.