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

Since two angles are supplementary, their measures add up to 180 degrees. Therefore, we have the equation:

m<ACB + m<BCD = 180

Substituting in the given measures:

4x + (6x + 50) = 180

Combining like terms:

10x + 50 = 180

Subtracting 50 from both sides:

10x = 130

Dividing both sides by 10:

x = 13

Therefore, the measure of <ACB is:

m<ACB = 4x = 4(13) = 52 degrees. Answer: \boxed{52}.