Answer:
5
Step-by-step explanation:
Since it is an equilateral triangle so all the sides are equal
So
We can take a relation of any two sides
2y=y+5
2y-y=5
y=5
Hence y is equal to 5
if y=5, 5+5 is 10
2y is 2×5 which is 10, which is equivalent to the other 10
