Question 404841
Taking the angle of the triangle to be:

A=2x+20; B=x+25; C=2x-15.

The sum of angle in a triangle is equal to 180°

Sum up the angles:        A+B+C=180°
                         (2x+20)+(x+25)+(2x-15)=180
Clear the parentheses     2x+20+x+25+2x-15=180
                          5x              =180-20-25+15
                          5x              =150
Divide through by 5:       x              =30

For Angle A:    A=2x+20
                A=2(30)+20
                A=60+20
                A=80°

For Angle B:    B=X+25
                B=30+25
                B=55°

For Angle C:    C=2x-15
                C=2(30)-15
                C=60-15
                C=45°