We have been told that Lena finished her history assignment in 5/8 hours. Then she completed her English assignment in 1/2 hours and we asked to find out how much more time did Lena spend on her history assignment.
To find out the more time spend on history assignment we will subtract the time Lena spent on English assignment from time spend on history assignment.
Now we will make our denominators equal.
Therefore, Lena spent 1/8 hours more on history assignment.