Question

the diagram shows a triangle.
what is the value of a?
( a = square^circ )

Explanation:

Step1: Sum angles to 180°

$$(9a-20^\circ)+(23a-23^\circ)+(4a+7^\circ)=180^\circ$$

Step2: Combine like terms

$$9a+23a+4a -20-23+7=180$$
$$36a - 36=180$$

Step3: Isolate variable term

$$36a=180+36$$
$$36a=216$$

Step4: Solve for $a$

$$a=\frac{216}{36}$$

Answer:

$a=6$