Two angles are supplementary if the sum of their measures equals \(180^\circ\). Given that:
\[ m∠ACB = 4x^\circ \] \[ m∠BCD = (6x + 50)^\circ \]
We can set up the equation:
\[ m∠ACB + m∠BCD = 180^\circ \]
Substituting the expressions for the angles into the equation:
\[ 4x + (6x + 50) = 180 \]
Simplifying the left side:
\[ 4x + 6x + 50 = 180 \] \[ 10x + 50 = 180 \]
Now, subtract \(50\) from both sides:
\[ 10x = 130 \]
Next, divide by \(10\):
\[ x = 13 \]
Now, we can find \(m∠ACB\):
\[ m∠ACB = 4x = 4(13) = 52^\circ \]
Thus, the measure of \(∠ACB\) is:
\[ m∠ACB = 52^\circ \]