Please help what is the answer?

12

Step-by-step explanation:

The altitude divides the hypotenuse into parts using this proportion

6/n = n / 18                Cross multiply

n^2 = 6 * 18

n^2 = 108

n = sqrt(108)

n = sqrt(4 * 9 * 3)

n = 2*3 *sqrt(3)

n = 6*sqrt(3)

Now use Pythagoras to get m. m is the hypotenuse of the small triangle on the left

m^2 = n^2 + 6^2

m^2 = 6^2 *sqrt(3)^2 + 36

m^2 = 36*3 + 36

m^2 = 108 + 36

m^2 = 144

m = sqrt(144)

m = 12

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.