X to the power of two thirds <span />
The answer is b. It is the only choice that equals the right answer. You could also write this as 3 * 10^4, which is equivalent to b.
Let:
v = Olga's speed
t = the time Anna spent going to school (3 km/hour)
t/2 = the time Anna spent running back home with speed of 6 km/hour
So, t + t/2 = 3t/2 is the total time
In the meantime distance = speed*time and the both made the same distance we can put it as:
3t + 6*(t/2) = (3t/2)*v
6t = (3/2)tv divide both sides by t
(3/2)v = 6
v = 2*6/3
v = 4 km/hour
Olga's speed was 4 km/hour.
3(5x+2)=8x+20
15x+6=8x+20
15x-8x=20-6
7x=14
then you divide both sides by 2
The answer is 2.
