5) The angles are vertical so they are congruent.
3x - 10 = 2x + 30
3x = 2x + 40
x = 40
6) To calculate x we will have to find a first.
5a + 4a = 180 because they are on a straight line.
9a = 180
a = 20
Now we will find the value of 5a because x is vertical to the angle, hence they are congruent.
So 5a = 5(20) = 100
So angle x is also 100.
7) First we will find the value of x.
6x - 25 = 4x + 15
6x = 4x + 40
2x = 40
x = 20
The value of y can be found now by setting 4x + 15 + y = 180 becuase they are on a straight line.
4(20) + 15 + y = 180
80 + 15 + y = 180
95 + y = 180
y = 85.
Hope this helps :)
