Answer:
C. 700 km/hour
Step-by-step explanation:

Solution:
Given PRQ is a triangle.
ST is a line parallel to RQ.



<u>Triangle proportionality theorem,</u>
<em>If a line parallel to one side of a triangle intersects the other two sides, then it divides the two sides proportionally.</em>


Do cross multiplication, we get

Divide by 2x on both sides, we get

Answer:
1
1 is the only integer that can go into 5 as 5 is a prime number