Answer:
55°
Step-by-step explanation:
Assuming you are looking for the angles and not the length of the sides, the remaining angle is 55°. All 3 angles have to equal 180°.
A+B+C=180
A+75+50=180
Subtract 75 and 50 from 180 to get:
A=55
My guess is -1 because when a x value don’t got a number replace it with a 1
It can be b), c) and d).
b) because it says the sum of three angles — this one’s the most obvious, as we can look at x, y and z as three different angles that sum up to 180.
c) works because 3a is, in essence, a + a + a, which we can look at as the sum of 3 angles that adds up to 180.
d) because we already have 2 angles, and “a” is just an unknown angle. It all sums up to 180.
a) and e) dont work because they involve multiplying (x*y*z and x*x*x) and the problem says we need to look for the sum of angles, not the product. :)
First, simplify the negative addition. 
Follow the order of operations by dividing first. 
Add and subtract from left to right. 
