Answer:
60%
Explanation:
There are 10 total kits.
6 of those are planes.
So the fraction of kits that are planes is 6/10. Make sense?
Good, now just evaluate that to 0.6. Good? 6 ÷ 10 = 0.6
Now the conversion piece you need to memorize: to convert a decimal to percent, multiply by 100.
The reason why is that percent literally means "per century," or "per 100." So in this example, if there were actually 100 kits, then there would be 60 planes (same ratio), and 60 out of 100 kits would be planes. 60 per hundred, 60 percent. Please take the time to understand this paragraph; it'll save you so much time the rest of your life.
So to finish: 0.6 x 100 = 60, which means that 60% of the kits are planes.
If you want a formula: 6/10 x 100 = 60%
More generically: a/b x 100 = %
I hope the discussion helped, rather than just tell you the answer.
Take care.