Answer:
5y +6 +7y = 2 (6y + 3 )
Explanation:
We can name the blanks 'a' and 'b'. Then we have ...
5y +6 +7y = a(6y +b)
This will have infinitely many solutions when both sides simplify to the same expression.
12y +6 = 6ay +ab
To have these expressions be the same, we must have ...
12 = 6a . . . . same coefficient of y
6 = ab . . . . same constant
The first of these equations tells us ...
a = 12/6 = 2
Then the second equation tells us ...
b = 6/a = 6/2 = 3
The equation with the blanks filled in is ...
5y +6 +7y = 2 (6y + 3 )