## Elementary Algebra

Let the first unknown angle be $x$ degrees. Since the second angle is twice the first, we let the second unknown angle be $2x$ degrees. Since the sum of the three angles of a triangle is always $180$ degrees, we write the following equation and solve: $x+2x+75=180$ $3x+75=180$ $3x=180-75$ $3x=105$ $x=\frac{105}{3}=35$ Therefore, the first unknown angle is $35$ degrees while the second unknown angle is $35(2)=70$ degrees.