+394 Find the measure of each marked angle. Assume the lines are parallel.
Two parallel lines that rise from left to right intersect a horizontal line, each forming four angles. Where the line on the left intersects the horizontal line, the top right angle measures (x plus 1) degrees.
Where the line on the right intersects the horizontal line, the top left angle measures (9x minus 21) degrees.
left parenthesis x plus 1 right parenthesis degrees(x+1)°
left parenthesis 9 x minus 21 right parenthesis degrees(9x−21)°
x+1= ____°
9x−21= ___°
(Simplify your answers. Type an integer or a fraction.)
+9481 
These angles are supplementary, so...
(x + 1)° + (9x - 21)° = 180°
x + 1 + 9x - 21 = 180
Combine x and 9x to get 10x , and combine 1 and -21 to get -20 .
10x - 20 = 180
Add 20 to both sides of the equation.
10x = 200
Divide both sides of the equation by 10 .
x = 20
So....
x + 1 = 20 + 1 = 21
9x - 21 = 9(20) - 21 = 159
+9481
These angles are supplementary, so...
(x + 1)° + (9x - 21)° = 180°
x + 1 + 9x - 21 = 180
Combine x and 9x to get 10x , and combine 1 and -21 to get -20 .
10x - 20 = 180
Add 20 to both sides of the equation.
10x = 200
Divide both sides of the equation by 10 .
x = 20
So....
x + 1 = 20 + 1 = 21
9x - 21 = 9(20) - 21 = 159
