To find the value of \( x \), we start by using the fact that the two angles are adjacent and together they form a \( 90^\circ \) angle. This means that:
\[ (x + 4) + (3x + 2) = 90 \]
Now we can combine like terms:
\[ x + 4 + 3x + 2 = 90 \]
This simplifies to:
\[ 4x + 6 = 90 \]
Next, we will isolate \( 4x \) by subtracting \( 6 \) from both sides:
\[ 4x = 90 - 6 \] \[ 4x = 84 \]
Now, divide both sides by \( 4 \):
\[ x = \frac{84}{4} \] \[ x = 21 \]
Thus, the value of \( x \) is \( \boxed{21} \).