Explain the Error Find the error in the solution, and then solve it correctly.
7x + 21 + 3x = 2
7x + 21 = -1
7x = -22
X=
-22
7
(select) was subtracted from the left side, but (select) was subtracted from the right side. The
Subtraction Property of Equality states that you can subtract the same number from each side and the
equation will remain true. But 3x and 3 are not the same number (unless x is 1
X =

3x then 3 then 0

Step-by-step explanation:

:)

step-by-step explanation:

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.