## Introductory Algebra for College Students (7th Edition)

18$^\circ$, 72$^\circ$, and 90$^\circ$
The sum of the measures of the angles of a triangle is always 180$^\circ$. x+4x+5x=180 5x+5x=180 10x=180 x=$\frac{180}{10}$ x=18$^\circ$ 4x=4(18)=72$^\circ$ 5x=5(18)=90$^\circ$