A physics student spends part of her day walking between classes or for recreati

Question

A physics student spends part of her day walking between classes or for recreation, during which time she expends energy at an average rate of 270 . The remainder of the day she is sitting in class, studying, or resting; during these activities, she expends energy at an average rate of 100 .

If she expends a total of 1.5×107 of energy in a 24-hour day, how much of the day did she spend walking?

Hello, I don't know how to solve this problem .. but I took the answer from a site
and the answer is 10.39 hours but the system said that it's wrong and try again
and when i submitted it , they give me a note which said :

Very close. Check the rounding and number of significant figures in your final answer.

Can you help me ??
:(

Explanation / Answer

let number of hours walking = k then , k x 270 x 60 x 60 + (24-k) x 100 x 60 x 60 = 1.5 x 10^7 So, 972k + (24-k)x 360 = 15000 So, 612 k = 6360 So, k = 10.392156..... hours. = 10 hours 23.52936 minutes = 10 hours 23 minutes 32 seconds.

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