If the function \( f(x) = 2x + 3 \), find the equation of the function when \( f(x) = 5 \).

Step 1 ：Start by substituting \( f(x) = 5 \) into the equation \( f(x) = 2x + 3 \). So, we get \( 5 = 2x + 3 \).

Step 2 ：Next, we rearrange the equation to make \( x \) the subject. So, we get \( 2x = 5 - 3 \).

Step 3 ：Then, we simplify the right-hand side of the equation to get \( 2x = 2 \).

Step 4 ：Finally, we divide each side of the equation by 2 to find the value of \( x \). So, we get \( x = \frac{2}{2} \).