Question 774131
n1 + n2 = 180
n2 = 20 + 3(n1)
 

n1 + n2 = 180
n1 + 20 + 3n1 = 180
4n1 + 20 = 180
4n1 = 180 - 20
4n1 = 160
4n1 / 4 = 160 / 4
n1 = 40 degrees ans.

n2 = 20 + 3(40)
n2 = 140 degrees ans.

checking:

n1 + n2 = 180
40 + 140 = 180
180 = 180