12. which equation is an identity? a. 7 - (9x + 3) = -9x - 4 b. 6m - 5 = 7m + 5 - m c. 10p + 6 - p = 12p - 3(p - 2) d. 3y + 2 = 3y - 2 13. which equation has no solution a. 5y + 3 = 5v - 5 b. 2x - 4 = 2x + 7 - x c. 2y + 5 - y = 2y - 3(y - 6) d. 7z + 9 = -7z - 6 14. solve the following equation 2(h-8) - h = h - 16 a. h = b. h = c. infinitely many solutions d. no solution

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.