Start with

Add 2x to both sides:

Subtract 21 from both sides:

Divide both sides by 5. Since it is positive, we don't have to change the inequality sign:

So, the answer is 
Answer:
The athlete will run 200 kilometers.
A atleta percorrerá 200 quilômetros no total.
Step-by-step explanation:
She will run x kilometers.
She has already run 5/8 of the distance(5/8 of x), and still needs to run 75 kilometers.
So






The athlete will run 200 kilometers.
A atleta percorrerá 200 quilômetros no total.
Answer: x=0 or x= -5/6
Step-by-step explanation: x=((−2)(3))(x2)−4x