The difference between the two angles formed when two straight lines intersect = 42. Find the angle between the given lines.

Let us express the degree measure of the first adjacent angle, for which we use the variable a.
Consequently, the degree measure of another adjacent angle will be 180 – a by definition.
Since we know from the condition of this task that the difference between these two angles is 42 °, then we write down the equation and find out what is the degree measure of these resulting angles:
a – (180 – a) = 42;
a + a – 180 = 42;
2a = 222;
a = 111;
180 – 111 = 69.
Answer: When crossing, 2 angles of 111 ° and two angles of 69 ° will be formed.