To make this easier, we can convert the fractions into decimals. 3/4 is 0.75. 1 and 1/2 would be 1.50 and 2 and 1/4 would be 2.25. Now, let us to the subtraction in order for us to know the difference of each. So 1.50 minus 0.75 would be 0.75. And 2.25 minus 1.50 is also 0.75. 0.75 is 3/4 and this means that she increased 3/4 hour each day.