You have to distribute the 7 to the y also. So the new equation should be 7y-35. When using the distributive property you are supposed to distribute the number outside of the parentheses to every number inside of the parentheses.
The mistake that has been made is when you distribute the 7 to -5 and y on the left side of the equation it ends up being 7y-35, but 7y is not equivalent to y.
