Calculate the Sum: 5.3 + 2.45 Decimal Addition

To solve this problem, follow these steps:

• Identify the given numbers: $5.3$ and $2.45$.
• Align them by the decimal point:

  5.30
+ 2.45
------

Note that adding a zero to the right of $5.3$ makes it $5.30$, which does not change its value but ensures alignment.

Next, perform the addition starting from the rightmost digit:

• Hundredths place: $0 + 5 = 5$
• Tenths place: $3 + 4 = 7$
• Units place: $5 + 2 = 7$

Thus, the sum is:

  5.30
+ 2.45
------
  7.75

The sum of $5.3$ and $2.45$ is $7.75$.

Therefore, the correct choice corresponding to our solution is choice 1: $7.75$.