Question 773800
n1 + n2 = 180
n2 = 20 + 3(n1)
 

n1 + n2 = 90
n1 + 10+ 4n1 = 90
5n1 + 10 = 90
5n1 = 90 - 10
5n1 = 80
5n1 / 5 = 80 / 5
n1 = 16 degrees ans.

n2 = 10 + 4(16)
n2 = 74 degrees ans.

checking:

n1 + n2 = 90
16 + 74 = 90
90 = 90