Question

What should I fill the blanks with?

Answer 1

Answer:

The three angles form a "linear triplet" ,  so their measures must add up to $180^o$

Step-by-step explanation:

Notice that the three angles add up to cover half a circle (therefore 180 degrees of angle. Such type of angle combination is called a "linear triplet" since they add up to give a straight line.

Answer 2

Linear triplet and 180°