1st scenario: angles 1 and 2 form a linear pair and add up to 180
2nd scenario: angles 1 and 4 are same-side interior and add up to 180
3rd scenario: angles 1 and 8 are corresponding and equal; if angle 7 is 37.7 then angle 8 is 142.3 (they form a linear pair). Since angles 1 and 8 are equal then angle 1 is also 142.3
