Answer:
Rubi read for 21 minutes longer than Suhani.
Explanation:
The least common multiple (LCM) of 4 and 5 is 20.
Rubi read for 3/4 of an hour, which is equivalent to 15/20 of an hour.
Suhani read for 2/5 of an hour, which is equivalent to 8/20 of an hour.
Since 15/20 is greater than 8/20, Rubi read for a longer time.
To find the difference, we can subtract the two fractions:
15/20 - 8/20 = 7/20
So Rubi read for 7/20 of an hour more than Suhani. We can also convert this to minutes by multiplying by 60:
7/20 x 60 = 21 minutes
Therefore, Rubi read for 21 minutes longer than Suhani.