Write each fraction as a unite fraction 12/84 13/143 23/138

A unit fraction is a fraction with a numerator of 1. With that in mind, we can reduce each of the three given fractions like this:

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