Question: I would love to understand how to solve this problem: Martin went on an eight-hour business trip. During the first half of the trip, he traveled at a speed of 70 kilometers per hour and during the second half at a speed of 85 kilometers per hour. How many kilometers did he travel during the journey?
Can you explain?
Answer: 
Half of the trip lasts for 8 * 0.5 = 4 hours.
During the first half, Martin did 4 * 70 = 280 kilometers.
And during the second half 4 * 85 = 340 kilometers.
In total Martin traveled 280 + 340 = 620 kilometers during his business trip.