Question

2 supplementary angles are in the ratio 2:7 find the measures of angles

Answer 1

2x+7x=180 9x=180 x=20 2x=40 7x=140 40 and 140 are the angles

Answer 2

let the angles be a and b 
they are in the ratio 2:7
let a=2k and b=7k
a+b=180 as they are supplementary
2k+7k=180
9k=180
k=180/9
k=20
then a=2k=2.20=40
and b=7k=7.20=140