Question

20: sum of angle measures: 180°

Explanation:

Step1: Set up the equation

The sum of angles in a triangle is \(180^{\circ}\). So, \((x + 20)+60 + 3x=180\).

Step2: Combine like - terms

Combine \(x\) and \(3x\), and constants \(20\) and \(60\). We get \(4x+80 = 180\).

Step3: Isolate the variable term

Subtract \(80\) from both sides: \(4x=180 - 80\), so \(4x=100\).

Step4: Solve for \(x\)

Divide both sides by \(4\): \(x=\frac{100}{4}=25\).

Answer:

\(x = 25\)