10 students of Elena's classmates like to make jewellery.
Explanation:
Let total no.of classmates who liked the jewellery = x
Here, in the given problem, given she asked her classmates '20'. So, it clearly shows that total number of students/classmates = 20. Also, in that, 50% said like to make jewellery. Now find 'x' as below,



Hence, the total number of classmates who liked to make Jewellery = 10