Please help! Only if you KNOw, I’m confused

40

Step-by-step explanation:

1.Kknow the following information;

Remember, the sum of degrees of angles in a triangle is 180.

So say if a traingle contained;

<1, <2, <3,

Then:

<1 + <2 + <3 = 180

2. State the given, and set up an equation;

In this case, it is given that;

<1 = 115

<2 = 25

Therefore, set up the equation;

115 + 25 + <3 = 180

3. Solve the equation;

115 + 25 + <3 = 180

Simplify,

140 + <3 = 180

Inverse operations,

140 + <3 = 180

-140          -140

<3 = 40

i believe the answer is c.

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.