Two angles are supplementary with measures m∠ACB=4x° and m∠BCD=(6x+50)°. What is the measure of ∠ACB?

Since the two angles are supplementary, their sum is 180 degrees. Therefore, we have the equation:

m∠ACB + m∠BCD = 180

Plugging in the given values, we have:

4x + (6x + 50) = 180

Combining like terms, we have:

10x + 50 = 180

Subtracting 50 from both sides, we have:

10x = 130

Dividing both sides by 10, we have:

x = 13

Finally, plugging this value back into the equation m∠ACB = 4x, we get:

m∠ACB = 4(13) = 52 degrees

Therefore, the measure of ∠ACB is 52 degrees.