Question

The ratio of three angle are 3:4:5 what is the highest angle of the triangle??

Answer 1

The sum of the sides of a triangle is equal to 180º.
The three angles will be: 3x,4x and 5x. 
we can suggest the following equation:
3x+4x+5x=180

12x=180
x=180/12
x=15

The angles would be:
3x=3(15)=45
4x=4(15)=60
5x=5(15)=75

Answer: the highest angle would measure 75º.