Peter knows that the distance an airplane travels between Spain and Russia is 7019 km, while the distance between Spain and Germany is 1615 km. Peter took a flight from Spain, which made a stopover in Germany, while being there, he receives a call from his brother asking him how many kilometers he has to fly to get to Russia and then return to Spain. What will Peter answer? Think carefully first, then make a decision:
Being 7019 km the distance from Spain to Russia. To get from Germany to Russia, Peter has to travel 7019 - 1615 = 5404 km. Knowing both distances, Peter will answer that he has to fly 5404 + 7019 = 12423 km. So, the answer is 12423.