Explain how to use prope Explain how to use properties to prove d + (8d + 1) + 7 is equivalent to 8 + 9d. rties to prove d + (8d + 1) + 7 is equivalent to 8 + 9d. HU 20 POOOIINNNTTSS

use this formula:

p(a\b) = p(a and b)/p(b).

take it from here.

second option

step-by-step explanation:

the measures of a triangle equal 180. use that to find x.

2x+3x+4x=180

9x=180

9x/9=180/9

x=20

now you know x, you know angle a is 40°, angle b is 60°, angle c is 80°.

because angle a is 40°, the first option doesn't work.

because angle b is 60°, the second option does work.

when you add angle a and b, you get 100°. complementary means it equals 90°, so the third option doesn't work.

when you add angle a and c, you get 120°, which is not 100.

in geometry, parallel lines are lines in a plane which do not meet; that is, two lines in a plane that do not intersect or touch each other at any point are said to be parallel. by extension, a line and a plane, or two planes, in three-dimensional euclidean space that do not share a point are said to be parallel.