A car travels the first 50km of its journey at an average speed of 25m/s snd the next 120km at an average speed of 80km/h. The car completes the lat part of its journey at an average speed of 90km/h in 35 minutes. Find the average speed for its entire journey ,giving your answer in km/h.

Answer:84,6km/hStep-by-step explanation:the whole journey was in the first part the car travels 50km, in the second part 120km and in the third part we can find it with a simple rule of three90km--->60 minX<--------35min= 52.5 km the car made in the last part50km+120km+52,5km=222.5km was all the journey and he made it in:the last part in 35min, in the second part we know that the car was going at 80km/h and that he made 120km so: 80km--->60 min120km--->90 minin the first part we know that the car was going at 25m/s and he made 50km. 25m/s*1km/1000m*3600s/1h= we obtain the speed in km/h=90km/h90km---->60min50km---->x=33,333 minThe whole journey last 33,333min+90min+35min=158.333minif we express that in hour = 158.333min*1hr/60min=2.63the car made 222.5km in 2.63 hourso the average speed was222.5---->2.63hrX--------1hr=84,6the average speed was 84,6km/h