To multiply the given numbers, we can use 0.75 instead of 3/4.
Then, we multiply using the standard algorithm.
Notice that the result must have 4 decimal numbers since that's the number of decimals both numbers have at the beginning.
Now, we can use the areas model to show a diagram about the multiplication.
Notice that we've got 3 wholes with 3/4 each, that gives us 2.25 because it's the sum 0.75 + 0.75 + 0.75 = 2.25.