7x + 5 = 6x + 9 + x - 4 (Distributive Property Of Equality)
7x + 5 = 7x + 5 (Combine Like Terms)
0 = 0 (Subtraction Property Of Equality)
As you see it's the same thing in both sides and if you solve it gives 0 = 0 because it would cancel each other out and since 0 is equal to 0 it's infinite many solutions.
