When solving these proportions we just remember when moving a number from one side to the other if it started in the numerator it ends up in the denominator and vice versa.
I'll do it in two steps here for teaching purposes; it's not too hard to go directly to the answer.
The answer you want will be 10.
Hope it helps!!
Answer:
72 yd / min
Step-by-step explanation:
The first thing is to fully calculate the distance traveled, each lap is 200 yards and how 6 laps would be:
200 * 6 = 1200
Now, let's divide the race into how the statement tells us:
1200 * 2/3 = 800
1200 * 1/3 = 400
That is, in the first 800 yards it goes to 80 yd / min and then in the remaining 400 yards it goes to 60 yd / min, let's calculate the time Rhea lasted:
800/80 = 10 min
400/60 = 6,667 min
Which means that in total it would be:
10 + 6,667 = 16,667
In other words, Rhea took 16,667 minutes to travel 1,200 yards, so the speed would be:
1200 / 16,667 = 72
Therefore the average Rhea speed was 72 yd / min
here is a contradiction because in one inequality x can be equal to 15 ; and in the other it cannot
