X+3.5=4

To solve the equation \( x + 3.5 = 4 \), you need to isolate \( x \).

1. Subtract \( 3.5 \) from both sides of the equation:

\[ x = 4 - 3.5 \]

2. Calculate the right side:

\[ x = 0.5 \]

So, the solution is \( x = 0.5 \).