Chapter R - Section R.1 - Real Numbers - R.1 Assess Your Understanding - Page 16: 44

$3+y=2+2$

The sum involves addition, so: "The sum of $3$ and $y$" means $3+y$. "The sum of 2 and 2" means $2+2$. In the statement "The sum of $3$ and $y$ is the sum of $2$ and $2$", the word "is" means the two quantities are equal. Thus, the given statement means: $3+y=2+2$