in triangle abc, the size of angle b is 5 times the size of angle a and the size of angle c is 13° less than 4 times the size of angle a. find the size of the angles
Sum of angles of a triangle = 180 a+b+c=180 a + (5a) + (4a-13) = 180 Simplify and solve for a: 10a-13=180 10a=193 a=19.3 b=5*19.3=96.5 c=4*19.3-13=77.2-13=64.2 Check: a+b+c=19.3+96.5+64.2=180 ok.
