Answer. 30 minutes
Explanation. If he walks 70 m in one minute how long will it take him to walk 2,100 m. Well, this is a simple division problem (you could also use a ratio box).
2100/70= 30. Hope this helps, let me know if it’s correct so others can use it :)
Good luck.
The square root of 80 is: 8.944
I do believe all of these but core elements can be determined by spectroscopy which includes the use of electromagnetic radiation. Both the surface and core temperature can be measured using light. Surface elements can be found because the absorption lines of different elements in the spectra of the star, but I haven't heard anything about using spectral analysis for core elements.
The answer might be B because the value is negative, and negative could mean slowing down.
It depends on how many hours!
1 hour = 40km
2 hours = 80km