Question 775607
n1 + n2 = 90
(3)n1 +n2 = 180

3n1 + n2 + n1 +n2 = 270
(4n1 + 2n2 = 270)/2

2n1 +n2 = 135
n2 = 135 - 2n1

135 - 2n1 + n1 = 90
n1 = 45......ANS.

n2 = 135 - 2n1
n2 = 135 - 2(45)
n2 = 45

checking:
n1 + n2 = 90
45 + 45 = 90

3(n1) + n2 = 180
3(45) + 45 = 180