Question

The measures of two angles of a triangle is in the ratio 4:5 .If the sum of these two measures is equal to the measure of the third angle ,Find the measures of all the angles

Answer 1

Let the angles be 4x, 5x 
and third angle will be 4x+5x = 9x
∴4x+5x+9x = 180°
⇒18x = 180°
⇒x = 10°

so, angles are 40°, 50° and 90°

Answer 2

let the angle be 4x and 5x.
their sum is 9x.
 4x+5x+9x=180
18x=180
x=180/18
x=10

4x=4*10=40
5x=5*10=50
9x=9*10=90