4. Since angles 1 and 2 are supplementary, this means they add up to 180 degrees. Make them add up to 180 in an equation and solve for a. Substitute a back into m∠2 to find your answer.
(11a + 19) + (6a - 9) = 180
Combine like terms.
17a + 10 = 180
Subtract 10 from both sides.
17a = 170
Divide both sides by 17 to isolate and solve for the variable a.
a = 10
Substitute 10 for a into m∠2.
6(10) - 9 ==> 60 - 9 = 51
The measure of angle 2 is 51 degrees.
______________________________________________________________
5. Since Ray BD bisects ∠ABC that means that both the formed angles are equal to each other, so make them equal to each other in an equation.
5y - 3 = 2y + 12
Add 3 to both sides.
5y = 2y + 15
Subtract 2y from both sides.
3y = 15
Divide both sides by 3 to isolate and solve for the variable y.
y = 5
