We can make everything have the same denominator so we can add, subtract, and compare them:
The common denominator between 2, 4, and 8, is 8.
7/8 = 7/8
1/2 = 4/8
1/4 = 2/8
The question is if Laura rowed more, less, or the same to the combined distance of Daniel and Annabelle:
Laura : 7/8
Daniel: 4/8
Annabelle: 2/8
4/8 + 2/8 = 6/8
So Daniel and Annabelle's distance combined is 6/8, which is less than Laura's:
7/8 > 6/8.
This means that Laura rowed more than Daniel and Annabelle.