Question

Find the measure of the three angles of a triangle, if the second is 18 degrees more than five times the first and the third is three times the measure of the first.

Answer 1

A, B, C.
B=5A+18
C=3A

Triangle sum theorem says that all three angle measures add to 180 degrees.
so
A + B + C = 180

substituting, we get
A + 5A + 18 + 3a = 180

and the resulting equation can be solved with simple algebra.