Supplementary angles have a sum of 180°
Therefore, we can add the expressions for Angles A and B and set their sum equal to 180.
( 7x - 15 ) + ( 2x - 3 ) = 180
Now we can combine like terms and use inverse operations to find the value of x:
( 7x - 15 ) + ( 2x - 3 ) = 180
9x - 18 = 180
9x - 18 + 18 = 180 + 18
9x = 198
9x/9 = 198/9
x = 22
Then Angle A will have a measure of 7x - 15 or 7• 22 -15 = 154 - 15 = 139°
m∠A = 139°
The measure of Angle b will be 2x - 3 = 2 • 22 - 3 = 44 - 3 = 41°
m∠ B = 41°
NOTE: 139 + 41 = 180