List the order to write and solve the equation for x:

Image of a Right Triangle with a 45 degree angle

(18x + 21)

x = _____
(5 points)

List these steps in the right order:
Combine like terms: 45 + 90 + 21
Subtract 156 from both sides of the equation
Divide both sides of the equation by 8
Write the equation ∠1 + ∠2 + ∠3 = 180°
x = 3

1. Write the equation ∠1 + ∠2 + ∠3 = 180°

2. Combine like terms: 45 + 90 + 21
3. Subtract 156 from both sides of the equation
4. Divide both sides of the equation by 8
5. x = 3