supplementary angles add up to 180°.
x = measure of such angle
x + 20 = measure of her sibling.
since "x" has 20 less than her sibling, then clearly her sibling has to have 20 more than "x".

Since the diameter of the cylinder is 10, its radius is half that, or 5, thus
Answer:
2
Step-by-step explanation:
|a+x|/2 − |a−x|/2 , if a=−2; x=−6
Evaluate this expression
Simply plug in the numbers
| -2 + -6 | /2 - |-2 - -6|/2
|-8| /2 - |4|/2
4 - 2
2
A line of symmetry basically is like a reflection of a shape, so your answer is D.