A b and c are positive integers A:B = 3:8 and B:C = is 6:11 What is the smallest possible value of a + b + c

the sum of all the angles in a triangle are equal to 180

so you can add   the 3 given angles together to equal 180:

5y + 2y + 2y = 180

or since all three angles have the same letter, combine the 3 angles to equal 180:

9y = 180