



 
Hi Roy, If I am driving my car at 50 km/h and increase my speed by 10 km/h then my speed d now is 50 km/h + 10 km/h = 60 km/h. In this situation it is appropriate to add the speeds. But this is not the situation you are in. The car was tavelling at an AVERAGE speed of 50 km/h. I don't know what my speed is at this moment but I increase my speed by 10 km/h. Since I didn't know my speed when I increased it I don't know what my new speed is. It's not the units that concern me in what you sent it's that you didn't ask a question so I am having trouble responding. Have a look at Penny's response to an earlier question. Does it help? Write back if you need more assistance. Harley  


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