Solve Decimal Addition: 0.75 + 0.35 Step by Step

To solve this problem, we will add the decimal numbers 0.75 and 0.35 by aligning them according to their decimal points:

• Step 1: Align the numbers vertically by their decimal points:

  $\begin{array}{c} \phantom{0}\\ \phantom{0} \quad 0.75 \\ + \quad 0.35 \\ \hline \end{array}$

• Step 2: Add the digits starting from the rightmost column (hundredths place):

  - Hundredths place: $5 + 5 = 10$. Write 0 and carry over 1 to the tenths place.
  - Tenths place: $7 + 3 + 1 = 11$. Write 1 and carry over 1 to the units place.
  - Units place: $0 + 0 + 1 = 1$.

• Step 3: Write the final sum by placing the decimal point correctly below the decimal points of the addends:

  $\begin{array}{c} 0.75\\ + 0.35\\ \hline 1.10\\ \end{array}$

The sum of 0.75 and 0.35 is therefore $\textbf{1.10}$, which can be simplified to $\textbf{1.1}$ by removing the trailing zero after the decimal point.

The correct answer is, therefore, $\textbf{1.1}$, corresponding to choice $3$.