Answer:
Yea that problem is a bit confusing,
2y should be double of what y is, which is 4x+5
Then 2y says 8x+15, when it should be 8x+10.
I feel bad cause I am sure the teacher is wrong on this, he/she had probably made a typo, or you made a typo, but that's ok! We all make typos!
The teacher would be extra rude if they marked you wrong on this, cause the question itself is not written "properly"