Answer:
57+x = 45
The sum means your adding numbers. it says the sum of 57 and a number x. That means you are adding 57 and the number x. which is written as 57+x. It says after that "is 45" so the sum or answer is 45.
You can also solve for x.. if you want to, the answer would be x=-12.
because.. 57+-12 = 45
Step-by-step explanation:
