Set measure of angle c = x
Measure of angle a is 13 less than measure of angle c, so the measure of angle a would be x-13
Measure of angle b is eleven less than four times the measure of angle c, so the measure of angle b is 4x-11.
Next add all of the angles and set them equal to 180 (all angles of TRIANGLES will add to 180).
X+(x-13)+(4x-11)= 180
6x-24=180
6x=204
X=34
So angle c=34, angle b=4(36)-11=125, angle a=34-13=21
You can check your work by adding them:34+125+21=180 bam!