Answer:
The time period will be ;
10 am to 10 : 52 am
(Then she will catch up at exactly 10:52 am , 30 seconds)
Step-by-step explanation:
In this question, what we simply want to calculate is the amount of time it will take Riko to cover same distance as Yuto.
Mathematically, at any point in time;
Speed = distance/time
Let the time we are looking for be x minutes
At x minutes , Riko will be at a distance of 0.35 * x = 0.35x miles
At x minutes, Yuto will be at a distance of 5.25 miles + 0.25 * x = (5.25 + 0.25x) mikes
Kindly note that, at the time x minutes, the distance covered would have been equal;
Thus;
0.35x = 5.25 + 0.25x
0.35x -0.25x = 5.25
0.1x = 5.25
x = 5.25/0.1
x = 52.5 minutes
Over a time period of 52.5 minutes, Riko will be behind her brother ;
Since Yuto left at 10 am, the time period will be ;
10am to 10:52 am