Question 679717
In any triangle: 

{{{angleA + angleB + angle C = 180}}}

The problem states:

{{{angle C = 3*angle A}}}

{{{angle B = angleA - 5}}}

Substitute angleB and angleC in the first equation with the right side of the second and third equations:

{{{angleA + (angleA - 5) + (3*angleA) = 180}}}

{{{5*angleA - 5 = 180}}}

Add 5 to both sides of the equation:

{{{5*angleA = 185}}}

Divide both sides by 5:

{{{angleA = 37}}}

{{{angleB = angleA - 5 = 37-5=32}}}

{{{angleC = 3*angleA = 3*37 = 111}}}

Solution check:

{{{37 + 32 + 111 = 180}}}