What is the sum?
8+(-12)
О-20
0-4
020

-4

Work: So, to get -4, we need to simplify the equation. If you see any equation with +(- that's subtraction. So, with the rule, this equation is basically 8-12, and that's -4.

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.