Question 1065485
Angles at B and  C are given in terms of angle measure at A.


{{{A+(27+3A)+(48+A)=180}}}


{{{5A+27+48=180}}}


{{{5A=180-27-48}}}


{{{5A=105}}}


{{{highlight(A=21*degrees)}}}, and you can evaluate angles at B and C.