Answer:
The angle is 50 degrees.
Step-by-step explanation:
You'll see, the angle that is on the left of the 70° angle has to be 110°, because a straight line has 180°.
Now, the inner angles of a triangle have to sum 180°. So if the lower angle is 110° (because you just calculated it), and the upper angle is 20°, the third angle is:
180° = 110° + 20° + x
180° = 130° + x
180° - 130° = x
50° = x
Now this third angle is on the bottom left part of the triagle, and it's 50°. It also opposite to the angle 1, which is the one you want to calculate. Because they are opposites, they are identical, meaning that they both are 50°. This is due to a geometrical rule.
