Answer:
20 degrees
Explanation:
The interior angles of a triangle must add to 180 degrees. Therefore,
∠A+∠B+∠C=180
We know that ∠A is 87, and ∠B is 73. So, we can substitute 87 in for ∠A, and 73 in for ∠B.
87+73+∠C=180
Combine like terms
160+∠C=180
Since we are trying to find ∠C, we have to get ∠C by itself. 160 is being added on to ∠C. Subtract 160 from both sides, because subtraction is the opposite of addition.
160-160+∠C=180-160
∠C=180-160
∠C=20
So, the measure of ∠C is 20 degrees