Answer:
60°
140°
Explanation:
From the given figures,
a. we use the concept of alternate angles.
Two parallel lines cut by a transversal will have equal alternate angles;
So;
6x + 12 = 7x + 4
collect like terms and solve for x;
6x - 7x = 4 - 12
-x = -8
x = 8
Now, 6x + 12 = 6(8) + 12
= 48 + 12
= 60°
b. Here we use alternate angles and angles on a line;
4x is an alternate angle to that angle to the left of 13x + 10
And sum of angles on a line = 180
4x + 13x + 10 = 180
17x = 170
x = 10
Now, 13x + 10 = 13(10) + 10 = 140°