What is 100% of the mass ?
Answer:
A. 
Step-by-step explanation:

I am joyous to assist you anytime.
A square has two parallel sides and four right angles.
M = - 1
- 2 = - 1 ( 2 ) + c
- 2 = - 2 + c
c = 0
y = - x
All the measures in a triangle are equal to 180 degrees.
Let the unknown angle= x.
40+89+x= 180
Combine like terms.
129+x= 180
Subtract 129 from both sides.
x= 51
The angle is equal to 51.
I hope this helps!
~kaikers