Given:
The measure of arc AB is (4y + 6)°
The measure of arc BC is (20y - 11)°
The measure of arc AC is (7y - 7)°
We need to determine the measure of arc ABC.
Value of y:
The value of y is given by

Substituting the values, we get;

Adding the like terms, we have;

Adding both sides of the equation by 12, we have;


Thus, the value of y is 12.
Measure of arc ABC:
The measure of arc ABC can be determined by adding the measure of arc AB and arc BC.
Thus, we have;



Substituting y = 12, we get;



Thus, the measure of arc ABC is 283°