Step-by-step explanation:
I'm wondering this too..
The mistake that Karen made was that in order to get the 8 to switch sides, it should have been subtracted rather than added. This is because it is positive on the left side and therefore must be negative when we switch it to the right side. A proper version of this problem would be below.
y + 8 = 15
y = 15 - 8
y = 7
I believe it’s B because everything equals 180 and then 180-70=10