we know that
Yuna swam
miles in the open ocean in
hours
so the average rate is equal to

Let
x------> the distance in miles of the first part
y-----> the time in hours of the first part
we know that
First Part
-------> equation A
Second Part
-------> equation B
Using a graphing tool -----> to solve the system equations
see the attached figure
The solution is the point

that means

therefore
the answer is
The distance in the first part was
