Solve for u.
8u - 7 = -4u + 5

u = 1

Step-by-step explanation:

Move the variable to the left-hand side and change the sign. 8u + 4u - 7 = 5. Move the constant to the right-hand side and change it's sign. 8u + 4u = 5+7. Now add the like terms. 8u + 4u = 12u. 5 + 7 = 12. Lastly, divide both sides by 12. 12u/12 cancels each other out. 12/12 = 1. u=1

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.