10 ppoints and brainliest if right parallel lines s and t are cut by a transversal, r, as shown.

what is the measure of angle 1?
20°
42°
138°
160°

How I got this

The alternate exterior angles (7x-2) and (6x+18) are congruent due to the fact that line s is parallel to line t.

Set the two expressions equal to one another. Solve for x

7x-2 = 6x+18

7x-2+2 = 6x+18+2 adding 2 to both sides

7x = 6x+20

7x-6x = 6x+20-6x subtracting 6x from both sides

x = 20

If x = 20, then we can find the measure of angle (7x-2)

7x-2 = 7*20-2 = 140-2 = 138

As a check, let's see what angle (6x+18) is too

6x+18 = 6*20+18 = 120+18 = 138

We get the same result for each angle, so that confirms x = 20 is correct.

Since angle (7x-2) is 138 degrees, this means

angle 1 = 180 - (7x-2)

angle 1 = 180 - 138

angle 1 = 42 degrees

the answer is c.

step-by-step explanation: