Answer:
The correct answer is 15 minutes.
Explanation:
In order to perform this exercise we must better understand the information we have. 
If one day Lashawna made 12 bracelets, and the next day with a difference of 2.5 hours made 22 bracelets, we can determine how many bracelets she made in 2.5 hours just by subtracting 22-12. 
22-12 = 10 bracelets in 2.5 hours. 
With this information we can begin to analyze how long it took Lashawna to make one bracelet. 
We could use a cross-multiplication. 
If 10 bracelets ----- 2.5 hours 
 1 bracelet ----- x hours
 10.x = 2.5 .1 
 X = 2.5: 10 
 X: 0.25 
Now it is very important to understand that 0.25 does not represent minutes, but hours. Since we have done the calculation in hours. Therefore a 0.25 in one hour equals 15 minutes. A 0.50 equals 30, a 0.75 equals 45 and so on. 
If you wanted to perform the calculation in minutes to make it clearer you could also do it. 
2 hours and a half equals 150 minutes. 
If 10 bracelets ----- 150 minutes 
 1 bracelet ----- x minutes 
10x = 150.1 
X = 150: 10 
X = 15 minutes. 
In this way we can verify that the correct answer is 15 minutes.