Question

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

Answer 1

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.