If a car had traveled 10 kmh faster than it actually did, the trip would have lasted 30 minutes less. If the car went exactly 30 km, at what speed did it travel?
Select the correct option:	A) 20 kmh	B) 25 kmh	C) 30 kmh	D) 35 kmh	E) 40 kmh

Rationale: "time = distance / speed difference in time = 1 / 2 hrs 30 / x - 30 / ( x + 10 ) = 1 / 2 substitute the value of x from the options . - - > x = 20 - - > 30 / 20 - 30 / 30 = 3 / 2 - 1 = 1 / 2 answer : a"
Answer: A